REPORT ON THE CRUSTACEA MACRTJRA. 17 



of pereiopoda have no pleurobranchiae, but cany an anterior and posterior arthrobranchial 

 plume attached to the pleurocoxal articulation. 



The gnathopoda, both first and second, have only a single arthrobranchial plume; 

 but whether they support a small mastigobranchia I have not been able to determine, from 

 a desire not to dismember too largely a unique specimen of an interesting character. 



The pleopoda are small and delicate appendages, each consisting of one long and one 

 very short filamentous branch, fringed with long cilia, to which the ova are attached by 

 thread-like fibres. The ova are very large and not very numerous, numbering about 

 twenty in our specimen. Unfortunately these were in too immature a condition to 

 enable me to determine the form and character of the future brephalos, or the stage at 

 which the young are hatched. 



The external plates of the rhipidura (or sixth pair of pleopoda) are Anomurous in char- 

 acter, but Macrurous in so far as that the appendages on the two sides are symmetrical. 



The telson is peculiar, and instead of terminating as a single-jointed plate, there 

 is a well-defined separation into an anterior and a posterior part by a joint-like line of 

 division ; the former has its coxa-marginal lobes, and the termination of the alimentary 

 canal corresponds with its posterior margin, whereas the posterior division articulates 

 with the former, and exists only as a movable plate. 



The entire animal suggests its being in an intermediate stage, and bears a con- 

 siderable generic resemblance to Glaucothoe of Milne-Edwards. But this latter has 

 been shown (Brit. Assoc. Keport, 1869) to be an intermediate form between the brephalos 

 and the adult Pagurus. Cheiroplatea, like Glaucothoe, not only carries five pairs of 

 pleopoda, but has the posterior pair equilaterally developed. It has, moreover, the 

 dorsal surface of the pleon protected by Crustaceous plates, all of which Glaucothoe 

 loses when, with increasing age, it fulfils the habits of its kind — takes to itself the shell 

 of a dead Mollusc, and so passes from a Macrurous to an Anomurous condition. 



Cheiroplatea appears in its adult condition to represent an intermediate link between 

 Cenobita and the trichobranchiate Macrura. But the remarkable feature appears to be 

 that its nearest allies in the Anomurous group belong to the phyllobranchiate condition 

 of Crustacea. It has an appearance strongly suggestive of its being allied to a Pagurus 

 that had failed to obtain a molluscous shell for itself, and had consequently retained some 

 of the Macrurous characters of its youthful condition. 



Its general appearance is not that of a swimming animal ; we may consequently 

 feel assured that it was brought up by the dredge from the bottom, which was about 

 half a mile from the surface of the ocean, south of New Guinea. In this case the 

 temperature of the bottom is not recorded. It was taken associated with Eiconaxius 

 acutifrons and a species of Ophlophorus. 



The arranoement and form of the chela? induce me to believe that the little creature 

 inhabited some abode where the flattened claws afforded an efficient operculum. This 



(ZOOL. CHALL. EXP. PART LII. — 1886.) Fff 3 



