STYLOCHEIRON CARIXATUM. 293 



Stylocheiron carinatum G. O. Sars. 

 Plate 12, figs, 6a-6cl. 



Intermediate Furcilia-Stage (figs. 6a-6c). — The frontal plate wath rostrum 

 constitutes a rather large triangle almost as long as broad and with the lateral 

 margins somewhat concave and the end very acute; the dorsal keel of the cara- 

 pace is low and placed much Ijehind its middle; the lateral margins of the 

 carapace are without any tooth. 



The eyes have the lower section well developed, while t!ie upper is small. — 

 The antennular peduncles are rather slender; the process from first joint reaches 

 a little beyond the end of next joint; second joint almost twice as long as broad, 

 somewhat shorter than the third; flagella unjointed, upper flagellum much 

 shorter and thinner than the lower which is about half as long as third peduncular 

 joint. — Antennae and maxillipeds showing the usual larval development; 

 two anterior pairs of thoracic legs rudimentary. 



First pair of pleopods witli the exopod setiferous; the two following pairs 

 are very oblong, undi\idcd; the posterior pairs rudimentary, scarcely visible 

 below the margin of the lateral plates. — Sixth abdominal segment as long as 

 the sum of the two preceding segments. — The m'opods reach much beyond the 

 middle of the telson. — Telson is four and a half times as long as broad, with the 

 distal part somewhat narrower than the proximal; the terminal margin (fig. 6c) 

 is long, with seven rather long, naked spines, increasing in length from the 

 median spine to the subangular pair; the intermediate pair of postero-lateral 

 spines are very long and strong, a little longer than the inner pair and both pairs 

 with about fi\-e or six fine spines along a good part of their inner margin; the 

 proximal third pair of the postero-lateral spines are rather small. 



The specimen is 2.S mm. long; it is somewhat pooiiy preserved so that I 

 may have committed some inaccuracy in the appendages on fig. 6a. — The 

 specimen is from Sta. 4611, October 18, 1904, Surface. 



Last Furcilia-Stage (fig. 6d). — The triangle formed by the frontal plate 

 and rostrum in the main as in the preceding stage, but the lateral margins are 

 nearly straight; the dorsal keel of the carapace is placed a little more forwards 

 but still considerably behind the middle. — Eyes a little more developed. — 

 Antennulae with the process from first peduncular joint a little shorter and the 

 still un(li\ided lower flagellum conspicuously longer than in the former stage. — 

 Endopods of first and second pairs of thoracic legs mon> than half developed, 

 with the full number of joints, and the relative size, shape, and tegumental 



