REPORT ON THE CRUSTACEA MACRURA. 731 



short, arid carries a long ecphysis ; the coxa supports externally a lunate calcified plate 

 that articulates with a rudimentary mastigobranchia, that is independent of any branchial 

 plume, while near it a plume is attached to the membranous articulation. 



The first two pairs of pereiopoda are short, slender, and chelate, and have the carpos 

 uniarticulate ; the basis carries a long ecphysis, and the coxa bears a short mastigo- 

 branchial plate. The posterior three pairs are simple in character, decrease successively 

 in length, and terminate in a sharp-pointed dactylos, of which the posterior is much the 

 shortest. 



The pleopoda are biramose, narrow, and subfoliaceous. The terminal pair forms the 

 outer plates of the rhipidura, which are subequal in length with the telson. 



The branchiae consist of twelve plumes and five mastigobranchial plates that are 

 short and club-shaped, but sufficiently long to be able to penetrate for some distance 

 between the plumes ; the arrangement may be seen in the following table : — 



Pleurobranchiae, 

 ArthrobrarichiEe, 

 Podobranchiee, 

 Mastigobranchia?, 



Of these the anterior are the smallest and the posterior the largest. 



The arrangement of the branchiae corresponds most closely with that of Notostomus, 

 Calymarina. and Hymenodora, and approximates to that of Nematocarcinus, Campy- 

 lonotus and Oplophorus, from which it departs chiefly in the smaller number and less 

 important condition of the mastigobranchial plates. 



The plumes are attached to the body at a point nearer to the lower extremity than is 

 usual in this order, they being generally suspended more centrally. 



Geographical Distribution. — The species that belong to this genus were taken by 

 the Challenger in the Atlantic, off the south-eastern coast of South America, at 

 a depth of 2040 fathoms, off the north-eastern coast of Australia in 2440 fathoms, 

 south of Japan in 2425 fathoms, and in the Indian Ocean, 600 miles south of 

 Australia, at a depth of 2150 fathoms. Other species were obtained off New Zealand 

 in 1100 and 700 fathoms, off the Kermadec Islands in 600 fathoms, close to Japan 

 in 500 fathoms, and in the shallow sea between Australia and New Guinea in 200 

 fathoms. 



Acanthephyra acantkitelsonis was taken in Mid Atlantic at only two stations, not 

 far from the ecpiator, in depths of 1500 and 1850 fathoms respectively. 



Acanthephyra brachytelsonis has been found in five different localities, namely, off 

 the Kermadec Islands in from 250 to 630 fathoms, south of the Philippine Islands in 500 

 fathoms, off the south-eastern shores of South America, associated with Acanthephyra 

 agassizii, at a depth of 2040 fathoms, close to the southern shore of Japan at depths 



