REPORT ON THE CRUSTACEA MACRURA. 29 



The following table shows the arrangement of the branchiae as observed in Callianassa 

 longirnana : — 



Pleurobrancbiae, . . . . 



Aithrobrancbiae, . • . . ...22222... 



Podobranchue, . . . . 



Mastigobranehiae, . . . . 1 



h i k 1 in n o 



By this it will be seen that all the branchial plumes are absent, except those of 

 the artkrobranchia?, and the mastigobranchiae are wanting on every appendage except 

 the first pair of gnathopoda, where one is seen in the form of a rudimentary bulb. 



Geographical Distribution. — Eighteen species of this genus have been described, and, 

 from the various localities recorded, they appear to be sparsely scattered all over the 

 globe. Some are stated to belong to the western coast of North America, and two to 

 the western coast of South America; two to the eastern coast of North America, 

 including the West Indies; one is from Europe, two from the western coast of Africa, 

 including Cape Verde ; the rest from the Pacific and islands of the Indian Ocean. 



This scattered distribution suggests that the small number of specimens found is due 

 to the burrowing habits of the animal rather than to paucity of specimens. 



Geologically, Callianassa has only been found in the more recent series of formations. 

 The largest specimen, Callianassa maxima, A.. Milne- Edwards, stated to have been found 

 at a great distance from the sea, in alluvial soil, on cutting a canal in Siam. Another, 

 Callianassa crassa, A. Milne-Edwards, was found in the Miocene sands of St. Paul, near 

 Dax. Others have been recorded from the Calcaire grossier de Parmes, and the Environs 

 of Gisors ; the sands of Beauchamp, and the Chalk formation of Bohemia, according to 

 Anton Fritsch, have yielded six species. 



Callianassa occidental!*, n. sp. (PI. II. fig. 2k). 



The propodos is smooth, longer than broad, and broader than the carpos, which is 

 also longer than the palm, or that portion of the propodos that does not include the 

 pollex. Meros as long as the carpos, the lower margin compressed to a thin convex plate 

 posteriorly serrate. Ischium long, flexed, imperfect. 



Habitat— Station 23, March 15, 1873; hit. 18° 24' N., long. 63° 28' W.; off Sombrero 

 Island, West Indies ; depth, 450 fathoms ; bottom, Pteropod ooze. Associated with 

 Cherarnus occiclentalis. 



A solitary specimen of the larger of the first pair of pereiopoda is all that was taken 

 of this animal. This limb appears to differ from that of any known species, more 

 particularly from that of Callianassa major (Say), the only one that has been taken in the 

 same neighbourhood, and which is described as having the meros armed with a very strong 

 tooth. It is not impossible that it may belong to the species Cheramus occiclentalis, but 

 it is too large to have belonged to the specimen with which it was taken. 



