214 



THE VOYAGE OE H.M.S. CHALLENGEE. 



margin of the carapace ; the first three joints of the peduncle appear to have com- 

 pletely coalesced, and are much broader than the next two, the former on the 



outer anterior margin carries a large bat-shaped scapho- 

 cerite, of which the outer margin is straight and armed 

 with five denticles; the inner is rounded and fringed 

 with long ciliated hairs articulated at the base. On 

 the inner and upper surface of the same joint is a short, 

 round, translucent bulb, shown in the annexed woodcut, to 

 which I believe de Haan refers when he says, " Anten- 

 narum inferiorum articulus primus latere interno lobo 

 membranaceo." 



The function or the homologue of this organ I am at 

 a loss to determine ; but it appears to pass beneath and 

 rest on the under side of the flat lateral tooth at the base 

 of the upper antenna. 



The mandible is strong and powerful, but the incisive 

 margin is smooth, with very slight indications of denticula- 

 tion ; it carries a strong, three-jointed synaphipod. 



The first pair of siagnopoda (e) are small, feeble, and 

 bilobed, each lobe being fringed on the inner side with 

 short spines or stiff hairs ; the outer lobe supports on 

 the outer side a short, slender branch tipped with one or two hairs. 



The second pair of siagnopoda (/) consists of two bilobed foliaceous rami, tipped with 

 short hairs, a rigid but slender ramus that gradually in a curve tapers to a blunt apex, 

 and a long thick mastigobranchia fringed with ciliated hairs that are much longer on the 

 anterior and posterior margins, in which last position they are much increased in length. 

 The third pair of siagnopoda (g) has a broad foliaceous lobe fringed with simple hairs, 

 a small two-jointed branch fringed with hairs on the outer margin, a long branch that 

 is slightly curved and terminates in a few hairs at the extremity, and at the base of the 

 latter a broad mastigobranchial plate that is divided into an "anterior and a posterior 

 portion by a transverse ridge, and is entirely free from hairs. 



The first pair of gnathopoda (h) is long, slender, and pediform ; the meros is much 

 longer than any other joint, and straight, the basecphysis consists of a very short basal and 

 a long, terminal joint fringed with a few ciliated hairs at the extremity. The coxa 

 supports a small mastigobranchial plate, to which is attached a podobranchial plume of 

 about the same length, at the base of which stands a small fasciculus of hairs. 



The second pair of gnathopoda (i and i") is long, slender, and pediform, having the 

 ischium rather longer than the meros : the basis is short and carries a short and almost 

 rudimentary ecphysis, of which the first joint is short and supports a terminal flagellum 



Fig. 41. — Second antenna of Spongicola 

 venusta. 



