108 bulletin: museum of comparative zoology. 



7. Rocinela laticauda, n. sp. 



Plate III. Fig. i-'i e. 



Three specimens of very different size, one a large and in all probability adult 

 male ; no female with marsupium. 



Head.^ The eyes of medium size, the shortest distance between them about 

 as long as the last joint of the peduncle of the antennae ; the distance in the 

 smallest specimen is comparatively a little shorter than in the largest one. 



AntennulcB. They surpass a little the middle of the last joint of the peduncle 

 of the antennae (Fig. 2 a) ; the peduncle reaching a little beyond the extero- 

 anterior angle of the third joint of the peduncle of the antennae ; the flagellum 

 in the small specimen with five, in the large specimens with six joints. 



AntennoE. They reach a little beyond the middle of the third thoracic seg- 

 ment ; the flagellum in the small specimen with fifteen, in the two other 

 specimens with sixteen joints. 



Thorax. The epimera (Fig. 2 b) of second and third thoracic segments 

 posteriorly rounded and not produced, those of the fourth segment somewhat 

 produced with rounded apex, those of the three posterior segments considerably 

 produced and almost acute. 



Thoracic Leys. The three anterior pairs (Fig. 2 c) tolerably stout : the fourth 

 joint with about four acute spines, some of them rather long ; the sixth joint 

 quite as broad as the fourth, its large and broad expansion on the inner side 

 with six spines. The four posterior pairs (Fig. 2d) with numerous slender 

 spines. 



Abdomen (Fig. 2e). The first segment is entirely concealed under the last 

 thoracic one. The abdomen increases very conspicuously in breadth from the 

 second to the fourth segment. The last segment is large and broad, posteriorly 

 very broadly rounded ; the dorsal surface is keeled anteriorly in the middle, 

 and from the keel towards the lateral margin it is rather deeply, or, in the 

 two smaller specimens, deeply and broadly depressed, the depression not 

 reaching the lateral margin ; the posterior margin with a number of very 

 small spines. 



Uropods (Fig. 2 e). They surpass a little the last abdominal segment. The 

 outer ramus reaches very little beyond the inner one, is considerably, but not 

 1|- times, broader than this, and is furnished with a number of spines on a 

 larger part of its exterior margin. The inner ramus with spines on the terminal 

 margin, and on the larger part of the outer margin. 



1 Scliiodte and Meinert write (Nat. Tidsskr., 3 R., Bd. XII. p. 383) on the species 

 of the genus Rocinela : "Bene recordari debet, discrimen, quod individua speciei 

 unius ejusdemque quoad figuram frontis atque sculpturam partis prioris trunci 

 prtebent, non sexura, sed jetatem diversam notare." This observation is a very 

 valuable one, as the differences in the front sometimes lead to great confusion. 

 The frontal plate seems to be very small in all species; the thoracic epimera show 

 much smaller differences in the various species than in the species of ^£'170. 



