Among the remarkable animals dredged by the ‘Lightning’ were the curious Echinoderm, Brisinga coronata, previously discovered by Sars, and the Hexactinellid sponges, Holtenia and Hyalonema, the Crinoids Rhizocrinus and Antedon celticus, and the Pennatulid Bathyptilum Carpenteri, not to mention numerous Foraminifera new to science.
In the spring of the following year, 1869, the Lords Commissioners of the Admiralty despatched the surveying vessel ‘Porcupine’ to carry on the work commenced by the ‘Lightning.’
The first cruise was on the west coast of Ireland, the second cruise to the Bay of Biscay, where dredging was satisfactorily carried on to a depth of 2,435 fathoms, and the third in the Channel between Faeroe and Scotland.
The dredging in 2,435 fathoms was quite successful, and the dredge contained several Mollusca, including new species of Dentalium, Pecten, Dacrydium, &c., numerous Crustacea and a few Annelids and Gephyrea, besides Echinoderma and Protozoa. A satisfactory dredging was also made in 1,207 fathoms.
The third cruise was also successful and brought many new species to light, including the Porocidaris purpurata, and a remarkable heart urchin, Pourtalesia Jeffreysi.
Concerning Pourtalesia Sir Wyville Thomson says:—
‘The remarkable point is that, while we had so far as we were aware no living representative of this peculiar arrangement of what is called “disjunct” ambulacra, we have long been acquainted with a fossil family—the Dysasteridæ—possessing this character. Many species of the genera Dysaster, Collyrites, &c., are found from the lower oolite to the white chalk, but there the family had previously been supposed to have become extinct.’
The discovery of two new Crinoids led to the anticipation that the Crinoidea, the remarkable group of Echinoderma, supposed at the time to be on the verge of extinction, probably form rather an important element in the abysmal fauna.
One of the most interesting results was the discovery of three genera in deep water, Calveria, Neolampas and Pourtalesia, almost immediately after they were discovered by Pourtales in deep water on the coasts of Florida, showing thus a wide lateral distribution and suggesting a vast abysmal fauna.
A year before the ‘Lightning’ was despatched, Count Pourtales had commenced a series of investigations of the deep-sea fauna off the coast of Florida. The first expedition started in 1867 from Key West for the purpose of taking some dredgings between that port and Havana. Unfortunately yellow fever broke out on board soon after they started, and only a few dredgings were taken. However, the results obtained were of such importance that they encouraged Pourtales to undertake another expedition and enabled him to say very positively ‘that animal life exists at great depths, in as great a diversity and as great an abundance as in shallow water.’