534 



THE VOYAGE OF H.M.S. CHALLENGER. 



Length, entire, 

 „ of carapace, 



Depth of carapace, 



Length of pleon, . 



„ of second gnathopod, 

 „ of large chela, 

 ,, of second pereiopod, 

 „ of telson, 



13 mm. (0-5 in.). 



4 „ 



3 „ 

 9 n 



5 „ 



4 ,; 



4-5 „ 



2-5 „ 



Habited.— Station 186, September 8, 1874 ; lat. 10° 30' S., long. 142° 18' K; off 



Cape York ; depth, 8 fathoms ; bottom, coral mud. One specimen. 



Dredged. 



The dorsal surface of the carapace is not elevated over the gastric region, and the 

 rostrum runs to a sharp point slightly directed upwards anteriorly. The orbital lobes 

 correspond much with those in Neptunus biunguiexdatus, and the ophthalmopoda 

 (fig. 2a, a) are hidden under the frontal margin of the carapace, which is not sufficiently 

 thin over the ophthalmus to permit of the latter being seen through it, but it is visible 

 in front when viewed anteriorly. 



The first pair of antennae (fig. 2b) has the first joint subequal in length with the 

 rostrum ; it is excavate on the upper surface and carries a large stylocerite, at the base 

 of which may be seen the acoustic apparatus in the form of a transparent spherical 

 chamber with a small round body within. The stylocerite is pointed and reaches beyond 

 the extremity of the first joint ; the second and third joints are shorter than the first, and 

 terminally support two flagella, the primary, which is the more robust, widens for a 

 distance and carries a considerable number of closely packed membranous cilia, after 

 which it rapidly narrows to a slender extremity ; the second flagellum is about twice the 

 length of the first and more slender ; it is about the length of the carapace. 



The second pair of antennae (fig. 2c) has a flagellum that is about the length of the 

 animal, and carries a scaphocerite that is a little longer than the peduncle of the first pair ; 

 it is broad and rounded at the extremity, and armed on the outer side with a short, stout, 

 sharp tooth, and on the inner and distal margins with long and ciliated hairs. 



The mandibles and oral appendages have not been examined in the solitary specimen. 



The first pair of gnathopoda (fig. 2h) apparently consists of only four joints ; the 

 basis, meros, and ischium appear to be united together to form a single joint, and from 

 a prominence near the base of this joint an ecphysis arises that is slender, flexible, 

 nearly double the length of the whole appendage, and multiarticulate almost from the 

 base to the apex, where there are a few unimportant hairs. The next joint is short and 

 probably homologises with the carpos, and the propodos articulates with it on its inner 

 rather than on its distal surface ; the latter is long, broad and curved, the lateral 

 margins being parallel, the anterior concave, and the posterior convex ; the distal 

 extremity is oblique, straight, and fringed with a series of numerous closely packed 



