It may here be remarked that the Molluscan fauna of the seas of North Australia and of the north-east coast from Cape York southwards to Sandy Cape, belongs to the great Indo-Pacific province, a zoological region extending from the east coast of Africa (from Port Natal or a little above, northwards to Suez) to Easter Island in the Pacific. But south of Sandy Cape and onwards to Van Diemen's Land (and apparently including New Zealand) we have a distinct (East)Australian province, marked by a peculiar fauna in many respects, representative of the Senegal, and perhaps also Lusitanian regions of the North Atlantic.
Proceeding in descending order we may first remark on the:
SHELLS OF SALT MARSHES.
As in the Northern hemisphere, Melampus or Convolvulus is the genus represented in such localities. Thus Auricula australis prevails in salt marshes at Brisbane Water, and an allied species in similar places in New Zealand. In both instances we find this form accompanied by members of a curious genus characteristic of the Australian province--Ampullacera, the Ampullacera quoyana being the Brisbane Water species, and A. avellana, that of New Zealand. In the latter case an Assiminea is its companion. A very curious fact noted during the expedition was the presence of a Unio living within the influence of salt water, in the River Brisbane.
SHELLS INHABIT MUD, ETC. AMONG MANGROVES.
These belong to the Indo-Pacific province. Some are found on the mangroves themselves. Such are the Littorina scabra, on the trunks and branches of mangroves among islets in Trinity Bay; a Phasianella inhabiting the trunks and branches of Rhizophora at the Percy Isles; a Littorina on the leaves of Aigaeceras fragrans at Port Curtis, Auricula angulata, and rugulata on the trunks of mangroves at Port Essington, and Monodonta viridis on their roots at Night Island; a new and very beautiful Ostrea was found on the roots of mangroves among Low Islets in Trinity Bay. In the last-named locality a Cytherea inhabited the mud around their roots. At the Three Islets several new species of Melampus, a Nerita and a Cyrena lived in a like habitat, and at Port Essington Cerithium kieneri, was found in the same situation. The fine Cyrena cyrenoides lives among the roots of mangroves in the Louisiade Archipelago.
LITTORAL ZONE.
Of the many living Gasteropoda taken in this region, very few are new species. Of Patelloid forms we have a new Fissurella and Parmophorus convexus at Port Dalrymple, accompanied by Haliotis naevosa, and species of Patella and Siphonaria. In the more tropical regions, Haliotis asinina and varia, another and distinct Patella, two Fissurellae and a Scutella were collected. Of convolute shells the littoral species gathered were all Indo-Pacific and inhabitants of mostly the coral-reef region, such as Cypraea arabica, annulus, isabella, errones and oryza, Conus magus, arenatus, achatinus, etc., Oliva cruentata, tremulina and ericinus, those of the last-named genus often living in sand. Bulla cylindrica occurred in sandy pools on the reef at Claremont Isles. Of Volutes, V. turneri lives on coral blocks at Port Essington, and V. undulata partially buried in sandbanks at Port Dalrymple. Conus maculosus is an inhabitant of the last-named locality. The Mitras found in the Littoral zone were all on the north-east coast, and well-known Indo-Pacific forms. A new Murex was taken on mud at Port Curtis. Fasciolaria coronata, Fusus alveolatus, and Triton verrucosus were found on the reefs at Port Dalrymple. Many species of Nassa, all known forms, were collected, mostly on mud in the Littoral zone, chiefly in the north-eastern province. Phos cyanostoma lives on muddy sand in the Trinity Bay islets, where also in similar situations is Terebra maculata and Pyramidella maculosa. Pyramidella auriscati is a littoral shell among the reefs of the Claremont Isles. Several Purpurae were taken on reefs and rocks at low-water; among them was P. textiliosa, a Port Dalrymple species. A Quoya lives on rocks being high-water mark in Lizard Island. Several Terebrae, including T. crenulata dimidiata and affinis, inhabit muddy sand among Pipon's Islets. The well-known Strombus luhuanus lives on sand among the reefs at Eagle Island. A Cerithium inhabits mud-flats at Port Molle and Pipon's Islets. Of the holostomatous gasteropods inhabiting the Littoral zone, the Naticae, mostly well-known species, were taken in sandy localities on the north-east coast, and the Neritae in the same province, mostly on rocks or reefs. Littorina pyramidalis and mauritiana are inhabitants of the rocky headlands of Broken Bay; other forms were collected at Port Curtis and at Port Dalrymple. At the last-named locality, Turbo undulatus, a new Risella, Monodonta constricta and buccata, and Trochus reticularis were taken on reefs. Littoral species of the same genera occurred on the north-east coast. A New Rissoa was found under stones at Night Island. Turbo squamosus and Trochus lentiginosus are inhabitants of the shore at Port Essington. In Broken Bay species of Bankivia and Scalaria were collected, cast dead on the shore.
The Acephala found living in the Littoral zone of the south-east Australian province were Cleidotherus chamoides, under rocks at low-water in Port Jackson; Mytilus erosus on the mud of zostera flats at Port Dalrymple, several species of Venus, Tapes, Cytherea in similar localities; Arca globata in the same habitat at Brisbane; Arca fuscata in reefs at Port Dalrymple; a new Tellina on mud at Port Phillip; another with Donax epidermia in sand at Broken Bay, and Clavagella australis on rocks at low-water, Port Jackson. Species of Pectunculus, Nucula, Pandora, Anatinella, Venus, Tellina (decussata and deltoidalis) and Mesodesma are thrown dead on the shores.
In the north and north-east Australian province the living littoral Acephala are Solens of which two new species were taken at Port Essington, Anomia australis, Anatina olerina, and another, new, in the same locality; species of Mytilus, Meleagrina and Pinna, Ostrea and Pecten (pyxidatus) Lima fragilis and squamosa, Hippopus and Tridacna, the former detached on coral reefs, the latter embedded in the coral, Corbis fimbriatus in sand among coral reefs; species of Venus, Cytherea, Circe, and Tapes in mud, Artemis sculpta at Port Essington on sand, Lucinae on sand or reefs, Crassatella on mudflats at Port Curtis, where Cypricardia vellicata occupies the fissures of rocks with Carditae; several species of Cardium in mud or sand, including C. fragum, C. subrugosum, and C. unedo; Sanguinolaria rugosa at Dunk Island; species of Mesodesma in sand, and Mactrae and Tellinae in mud; a new Psammobia at Port Essington as also a new Pholas that bores into coral. Other species, members of the same genera, are cast on shore dead.