91 



and larger than in Scy/l. sordidits, but, examined under a lens, these prominences prove to 

 be subdivided into smaller ones by little grooves. 



As regards the shape of the orbits and their situation just near the lateral border of 

 the carapace, both species resemble one another. 



The antennular segment resembles more that of Scyll. bicnspidatus than that of Scyll. sor- 

 didHs\ it is only twice as broad as long and, while it is notched anteriorly and grooved 

 in the middle line, each half presents in the middle a carinate tooth, that projects beyond the 

 anterior margin. 



The I*' abdominal somite resembles much that of Scyll. sordidtts. The posterior areolated 

 part is almost as large as the smooth anterior, it is hardly longer in the middle as 

 laterally and there are on each side lo or ii grooves, thai run parallel with the mid-dorsal 

 line; the areolae are somewhat longer than broad and the notch in the middle of the posterior 

 margin is as narrow and as deep as in Scyll. sordidus. In Stimpson's species, however, the posterior 

 sculptured part is shorter in the middle than laterally. The 2"<^ — 5''' terga are distinctly carinate 

 in the middle line; the carina of the 2"<^ somite and the somewhat longer and slightly arcuate 

 carina of the 3"^ are obtuse and hardly salient, the sculptured part of the 4''^ somite, however, 

 appears in the middle line distinctly longer than the 3'''' and the obtuse, strongly 

 curved carina of this somite is high and prominent, so that this somite presents 

 a gibbose appearance (Fig. iJ^l>), from which character the specific name has been derived. The 

 obtuse carina of the 5''' tergum is obvious, but very little prominent and appears nearly straight 

 in a lateral view; the 5'*^ tergum is just as long as the 3''''. The 2°'^ — 5''' terga show in the 

 mid-dorsal line a symmetrical, arborescent figure, which is more conspicuous than in Scyll. 

 sordidtis\ as regards the sculpture and the form of the squamiform prominences on the terga 

 and pleura and as regards the shape of the latter, both species agree with one another, but 

 the sculpture is more conspicuous in Scyll. gibberosiis. The 6* somite and the caudal fan present 

 no differences. 



In Scyll. sordidus, on the contrary, the 2"'' — 5"> terga can hardly be said to be carinate, 

 the carinae are obtuse, not at all prominent and the sculptured part of the 4''' tergum is 

 distinctly shorter than that of the 3"'. 



The proximal (outer) squame of the outer antennae (Fig. 14) is 3 mm. long and just as 

 broad, whereas in Scyll. sordidus it is distinctly longer than broad. The outer margin carries 

 three flattened teeth, that are not very shari* and gradually decrease in size in distal succession ; 

 the apex of the i"< is a little farther distant from the rather obtuse extreniit)- of this joint than 

 from its base and the apex of the 2"^' tooth is twice as far distant from that of the i^' than 

 from that of the small 3'"' tooth. On the left antenna there is a trace of a very small 4''> 

 tooth before the 3''''. The inner edge is armed with five or six teeth, the r' and the 

 2"'' are a little larger than the following; these teeth are somewhat unequal in size and mode- 

 rately sharp. The ridge on the middle of the upper surface is little prominent and has an 

 eroded appearance, when examined under the microscope; between this ridge and the teeth ol 

 the outer margin are situated about a dozen small tubercles or granules, that are 

 wanting in Scyll. sordidus. The anterior margin of the flagellum or distal squame is cut into five 



