REPORT ON THE CRUSTACEA MACRURA. 367 



the first maxilla becomes very rudimentary, and on the second maxilla the flabellum 

 (mastigobranchia) enlarges, the leg-like condition disappears, and large tubercles (Warzen) 

 are developed. The first maxillipedes like the rest of the feet (pereiopoda) lose the 

 flagellum (basecphysis)." 



The above are the notes in reference to the specimen taken by Dr. v. Willemoes 

 Suhni, and by the aid of his clearly drawn figure, may be compared with Acanthosoma 

 brevitelsonis on PI. LXIV. fig. 1. His drawing represents the ventral and mine the 

 dorsal aspect. 



In his figure the carapace is scarcely half the length of the animal and is but slightly 

 compressed at the fronto-lateral margin, and the frontal spines are represented as being 

 long, smooth, and situated posteriorly to the second pair of antennas ; whereas in my 

 specimen, which was probably captured about the same time and place, the spines are 

 slightly serrate and are undoubtedly situated at the outer angle of the frontal margin, 

 just above the second pair of antennas. In Suhm's drawing the rostrum is about two- 

 thirds the length of the carapace and serrate at the margins, whereas in mine the 

 proportional length of the rostrum is not so great and the surface is fringed with slender 

 hair-like processes, which perhaps under certain conditions may resemble a serrate margin, 

 The carapace in Suhm's specimen is armed at the margins with two lateral spinous 

 processes, but as the view given is that of the ventral surface, the dorsal spine at the 

 posterior margin, if it exists, cannot be seen. 



The five anterior somites of the pleon are laterally armed with spines ; in my 

 specimen all the spines are spinous, in Suhm's those on the fourth and fifth somites 

 are short and smooth. The telsons in all important points are similar. 



All the appendages are at the same stage in each ; the pleopoda, except the sixth pair, 

 are in a state of gemmation. 



Acanthosoma brevitelsonis (PL LXIV. fig. 1). 



The carapace is about half the length of the animal and but slightly compressed 

 laterally. The rostrum is long, straight, about half the length of the carapace, and fringed 

 with numerous short points or teeth. The frontal or cephalic region is advanced beyond 

 the rest of the carapace, from which it is separated by a constriction immediately behind 

 the second pair of antennas and anterior to the oral appendages. On each side, at the 

 outer angle, just above the second pair of antennas, a long spinous process, fringed with 

 numerous tooth-like points, projects. On each side of the outer lateral margin of the 

 carapace, just in a line with, or sbghtly anterior to, the mandibles, stands a second long, 

 flat, tapering spine-bke process, fringed with numerous teeth that are larger at the 

 base than at the apex ; posterior to this, on each side, and still on the lateral margin or 

 very close to it, stands a smaller spine-like process, furnished with fewer teeth or points ; 



