EEPORT ON THE ISOPODA. 79 



larger portion of these appendages are lost ; the general form of the body, apart from 

 the long spiny epimera, appears to be that of Desmosoma, while the characters of the 

 thoracic limbs are peculiar to the genus. The characters of Acanthocope spinicauda are 

 decidedly more aberrant (that is, compared to other genera) than those of Acanthocope 

 acutispina; the great length of the telson and the five-jointed uropoda are perhaps the 

 most remarkable structural features. The anterior thoracic limbs of this species agree 

 much more closely with Sars's description of Desmosoma, the first pair being decidedly 

 smaller than the rest, which are subequal ; on the other hand, the immense disproportion 

 between the anterior and posterior regions of the thorax is only comparable to a large 

 species, which I have described above (p. 71), under the name of Entry cope pellucida, 

 though I have pointed out that the generic identification of that species with Eurycope 

 is by no means certain. The distribution of spines on the dorsal surface of the body in 

 Acanthocope spinicauda is identical with that of Eurycope fragilis and the shape of the ' 

 caudal shield is, apart from the immensely elongated telson, not very different. The 

 styliform character of the uropoda, not to mention their being composed of six separate 

 joints, prevents me from regarding this species as a Eurycope. Although in Acantho- 

 cope spinicauda the posterior appendages of the thorax have quite the typical form that 

 they have in Eurycope, Desmosoma, &c, both species of this genus show a certain 

 approach to the Asellidse in the fact that the penultimate joint is not nearly so fitted 

 for swimming as in those genera, being much narrower ; in this respect all the three 

 posterior thoracic appendages are like the terminal pair in the genus Uyarachna (see 

 p. 77). There can be but little doubt that these two species belong to a distinct 

 genus from those already known, but the question is whether they are sufficiently alike 

 to be included in the same genus ; for the present I am inclined to unite them on 

 account of the general similarity in outward form. 



Acanthocope spinicauda, F. E. Beddard (PI. VIII. figs. 6-12). 



Acanthocope spinicauda, F. E. Beddard, Proc. Zool. Soc. Loud., 1885, pt. iv. p. 922. 



This species can be distinguished at once from any other Munnopsid by the extremely 

 long, slender telson, which is about half as long as the remaining portion of the body. 

 It presents other remarkable characters, and is one of the most curious forms of 

 Munnopsidae obtained during the voyage. A single specimen only was dredged between 

 Kerguelen and Australia in 1800 fathoms, at the same station as produced the remark- 

 able Ischnosoma bacillus. The specimen has been stained in picrocarmine and mounted 

 in Canada balsam. The specimen has been somewhat crushed in preparation ; the figure, 

 therefore (PL VIII. fig. 6), cannot be so accurate as might be wished. 



The specimen is a male, measuring 8 mm., inclusive of the long spiniform telson. 



As a rule this family of Isopods is not remarkable for the presence of pigment. Many 



