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



Habitat— Station 84, July 18, 1873; lat. 30° 38' K, long. 18° 5' W.; off the Canary 

 Islands ; depth and bottom not recorded. One specimen. 



Unfortunately only one very imperfect specimen was obtained ; all the pereiopoda are 

 gone, and its relation to N ematocarcinus can therefore only be conjectured, but, as it differs 

 in the important character of having a dactylos attached to the extremity of the second 

 pair of gnathopoda, it is impossible to associate it with any species of that genus. In the 

 other details of the portions preserved it closely resembles N ematocarcinus, differing 

 from N ematocarcinus cursor, A. Milne-Edwards, only in the number and character of 

 the spines on the rostrum. 



Notostomus, A. Milne-Edwards. 

 Notostomus, A. Milne-Edwards, Ann. d. Sci. Nat., ser. 6, torn. xi. p. 7, 1881. 



This genus was described by A. Milne-Edwards from specimens taken by Professor 

 Agassiz in the neighbourhood of the West Indian Islands, but some specimens were 

 previously taken by the Challenger, figured, and ready for publication. It is closely 

 allied in structural characters to Acanthephyra, and is only separated by the convenience 

 of classification in consequence of the external form of the carapace, which exhibits the 

 carinated features as seen in the genus Heterocarpus, with which its branchial arrange- 

 ment also corresponds. 



The body of the animal is not very much compressed laterally, except along the 

 dorsal ridge, which is elevated into a carina following the contour of the animal from the 

 rostrum to the telson. From the apex of the rostrum, corresponding with its infero- 

 lateral margin, a second carina longitudinally traverses the surface of the carapace along 

 the upper line of the branchial region to the posterior margin of the carapace. The 

 dorsal surface of the carapace is arched, especially over the frontal and gastric regions ; 

 the rostrum is horizontally straight. 



The ophthalmopoda are widely separated at their base, and carry a large ophthalmus 

 at their extremity. 



The first pair of antennae has the peduncle shorter than the rostrum, the first joint 

 being long and excavate on the upper surface to receive the ophthalmopod, and carries 

 a short, broad, and pointed stylocerite. The two following joints are short and carry 

 one stout and one slender flagellum, the former gradually tapering to a fine extremity. 



