Zoological Society. 223 



In the genus Apus, the tail-segment of the body is rounded, and 

 has no plate or prolongated appendage between the two long setse 

 or filaments. The first pair of feet are very long, dividing into three 

 cylindrical branches, the external one of which is very long, in some 

 species equalling in length the whole body with the tail filaments in- 

 cluded : they are very flexible, possess much motion, and are very 

 conspicuous. These organs at once distinguish the genus, and they 

 possess the same general character in all the species hitherto known. 

 Four species have only as yet been described, and I now propose to 

 add to that number a fifth. 



1. Apus cancriformis, Schseffer. Clypeo corporis plusquam 

 dimidiam partem tegente, ovato^ olivaceo, corneo ; ramo externo 

 pedum primi paris longitudine clypeum cequante. 



Long, toti corporis 2\ poll. ; lat. clypei 1^ poll. 



Pro Synonymis vide " Baird's Nat. Hist, of the British Entomos- 

 traca, Ray Society's Publications, 1850." 



Hah. In Europa ; detecta in Anglia, Gallia, Borussa, &c. In Africa 

 Septentrionali ; detecta in Tunisia, coUegit Dominus L. Frazer ; in 

 Algeria, coUegit M. Lucas. Museum Britannicum. 



The colour of this species is brownish yellow or olive clouded with 

 marks of a deeper hue. The carapace is oval and extends over nearly 

 two-thirds of the body of the animal. The keel which runs down the 

 centre of the carapace is pretty strong, and the deep notch at the 

 posterior extremity is lunated in shape and has its edges finely toothed. 

 The external branch of the first pair of feet is about the length of the 

 carapace, while the caudal setse are nearly as long as the whole body, 

 and are covered with numerous short hairs. The abdominal portion 

 of the body not covered by the carapace is studded all over with cir- 

 cular rows of stout hooked spines of a dark brown colour. 



2. Apus Guildingii, Thompson. Clypeo corporis vix dimi- 

 diam partem tegente, quadrato, membranaceo, nigrescente ; 

 ramo externo pedum primi paris longissimo^ totum corpus, Jila- 

 mentis caudalibus inclusis, excedente. 



Apus Guildingi, Thompson, Zoological Researches, Fasc. v. 108. 

 t. 6. f. 3 ; M. Edwards's Hist. Nat. Crust, iii. 561. 



Hab, In Insula " St. Vincent's," India Occidentali ; Rev. Lans- 

 downe Guilding. 



Mr. Thompson in his * Zoological Researches ' remarks : ** I re- 

 ceived this species of Apus together with the Artemis Guildingi 

 from the West Indies, and having as yet no details, must leave its 

 history in the hands of its distinguished discoverer. It is of a light 

 blackish colour, the clypeus translucent, almost membranous, and 

 shorter in proportion than in any of the known species, with the 

 extreme branch of the anterior member extremely long." Unfor- 

 tunately we have no further history of this species from its discoverer 

 the Rev. Lansdowne Guilding, but the short square-shaped cara- 

 pace and the extreme length of the external branch of the first pair 

 effect sufficiently distinguish it. 



3. Apus LONGiCAUDATUs, Le Conte. Clypeo corporis tertiam 

 partem non multo magis tegente^ rotundato, subfusco ; ramo 



