714 THE VOYAGE OF H.M.S. CHALLENGER. 



and third joints are short, cylindrical, and terminate in two flagella, of which the 

 inner is short and immature, and the outer is broken off. 



The second pair of antennas is long and slender, and carries a scaphocerite that is as 

 long as the peduncle of the first pair and armed with a small tooth on the outer distal 

 angle. The flagellum is slender, but it is broken off a little beyond the peduncle. 



The mandibles have not been examined. 



The first pair of gnathopoda is short and subpediform. 



The second pair (fig. 2/) is long, slender, and pediform ; it consists of six joints 

 and terminates in a sharp-pointed unguis that is flanked by two short hairs, and resembles 

 an unguiculate dactylos. 



The first pair of pereiopoda (fig. 2k) is robust, gradually increasing in diameter from 

 the meros to the propodos, whence it as gradually narrows to the extremity of the pollex, 

 which is pointed, and terminates in a sharp unguis ; the dactylos is short and apparently 

 in an immature condition, it is rounded at the distal extremity, shorter than the pollex, 

 and subapically tipped with a small spinule ; the ischium and meros are short, and the 

 basis carries a long, flat, and uniarticulate ecphysis. The second pair of pereiopoda 

 resembles the first in form and ajjpearance, but is a little longer and more robust ; the 

 dactylos, as in the first pair, is immature, and the basis is furnished with a similarly 

 formed ecphysis. The third, fourth, and fifth pairs are uniform in character and size, 

 they are subequal in length and terminate in a short, sharp dactylos ; only the third pair 

 is furnished with a basecphysis, which in form and appearance resembles those anterior 

 to it. 



The pleopoda are short and biramose, those of the sixth pair, forming part of the 

 rhipidura, have the outer margin smooth and the inner fringed with hairs. 



Observations. — The specimen from which the above description is taken is evidently 

 an immature animal, but one that has nearly attained the characteristic features of the 

 adult. The ophthalmopod may probably be relatively smaller in the mature specimen, 

 and the flagella of the first pair of antennas may be longer. The dactylos of the first 

 two pairs of gnathopoda has probably an unguis attached to its extremity, and it is 

 highly probable that the basecphyses, which resemble in appearance those of the genus 

 Oplophorus, may like them be persistent throughout life. The pleopoda probably 

 undergo a proportional change of size, but only a modification in form, and will have the 

 branches fringed with hairs, which in our specimen are not developed ; and the posterior 

 pair may become longer in relation to the telson. 



Caricyphus serramarginis, n. sp. (PI. CXXI. fig. 3). 



Carapace short, anteriorly produced to a horizontal rostrum, and dorsally armed ou 

 the frontal crest with a small papilla and a similar one on the cardiac region. 



