Tracheate Arachnids, with the last three segments of the cephalothorax free and the abdomen segmented. The chelicerae are largely developed and chelate, and the pedipalpi are leg-like, possessing terminal sense-organs.
The Solifugae are, in some respects, the most primitive of the tracheate Arachnida. Their general appearance is very spider-like, and by the old writers they are uniformly alluded to as spiders. The segmented body and the absence of spinning organs, however, make them readily distinguishable on careful inspection. They are for the most part nocturnal creatures, though some seem to rove about by day, and are even called “Sun-spiders” by the Spaniards. The night-loving species are attracted by light. They are, as a rule, exceedingly hairy. Some are extremely active, while the short-legged forms (e.g. Rhagodes, see p. [429]) move slowly. They are capable of producing a hissing sound by the rubbing together of their chelicerae. Only the last three pairs of legs are true ambulatory organs, the first being carried aloft like the pedipalps, and used for feeling and manipulating the prey.
There has been much controversy as to the poisonous properties with which these creatures have been very widely credited by both ancient and modern writers. The people of Baku on the Caspian consider them especially poisonous after their winter sleep. The Russians of that region much dread the “Falangas,” as they call them, and keep a Falanga preserved in oil as an antidote to the bite. The Somalis, on the other hand, have no fear of them, and, though familiar with these animals, have not thought them worthy of the dignity of a name.
Several investigators have allowed themselves to be bitten without any special result. Some zoologists have found and described what they have taken to be poison-glands, but these appear to be the coxal glands, which have an excretory function. Bernard[[325]] suggests that, if the bite be poisonous, the virus may exude from the numerous setal pores which are found on the extremities of the chelicerae. The cutting powers of the immensely-developed chelicerae are usually sufficient to ensure fatal results on small animals without the agency of poison. Distant,[[326]] indeed, thinks they cannot be poisonous, for when birds attack them they flee before their assailants.
The Solifugae require a tolerably warm climate. In Europe they are only found in Spain, Greece, and Southern Russia. They abound throughout Africa, and are found in South-Western Asia, the southern United States, and the north of South America. They appear to be absent from Australia, nor have any been found in Madagascar. Their usual food appears to be insects, though they devour lizards with avidity. Some interesting observations on their habits are recorded by Captain Hutton,[[327]] who kept specimens in captivity in India. An imprisoned female made a burrow in the earth with which her cage was provided, and laid fifty eggs, which hatched in a fortnight, but the young remained motionless for three weeks longer, when they underwent their first moult, and became active.
A sparrow and musk rats were at different times placed in the cage, and were speedily killed, but not eaten. Two specimens placed in the same cage tried to avoid each other, but, on coming into contact, fought desperately, the one ultimately devouring the other. It was noteworthy that the one which was first fairly seized immediately resigned itself to its fate without a struggle. As is the case with some spiders, the female is said occasionally to kill and devour the male. A Mashonaland species, Solpuga sericea, feeds on termites,[[328]] while a South Californian Galeodes kills bees,[[329]] entering the hives in search of them. They are fairly good climbers. In Egypt Galeodes arabs climbs on to tables to catch flies, and some species have been observed to climb trees.
Fig. [217].—Rhagodes sp., ventral view. Nat. size. a, Anus; ch, chelicerae; g.o, genital operculum; n, racket organs; p, pedipalp; 1, 2, 3, 4, ambulatory legs. (After Bernard.)
That their pedipalps, in addition to their sensory function (see p. [426]), possess a sucking apparatus, is clear from an observation of Lönnberg,[[330]] who kept specimens of Galeodes araneoides imprisoned in rectangular glass boxes, up the perpendicular sides of which they were able to climb for some distance by their palps, but, being able to obtain no hold by their legs, they soon tired.
External Anatomy.—The body of Galeodes consists of a cephalothorax and an abdomen, both portions being distinctly segmented. The cephalothorax consists of six segments, the first thoracic segment being fused with the two cephalic segments to form a sort of head, while the last three thoracic segments are free, and there is almost as much freedom of movement between the last two thoracic segments as between the thorax and the abdomen. The “cephalic lobes,” which give the appearance of a head, have been shown by Bernard[[331]] to be due to the enormous development of the chelicerae, by the muscles of which they are entirely occupied.