958 BB. n. J. HANSEN ON CIIUSTAOEANS [Dec. ] , 



times shorter and very narrow ; the first branchia above trl.^ is but 

 half as large as the corresponding one above trl.^, the second half 

 as large as the first but a little larger than the second above trl.^. 

 (In somewhat younger specimens with yellowish eyes all 4 branchito 

 are very distinct ; the animals are, for the rest, relatively shorter 

 and stouter.) The ext. br. of urp. without any spine on the 

 exterior margin, of which the ciliated part occupies from a little 

 more than the half to about three-lifths of the length. 



As to the half-grown larvoe, the representations of Kroyer and 

 Bate will be sufficient. — A younger larva, 6-4 mm. long, comcides 

 fairly well with S. utrinquedens, Bate (p. 433), in most respects, 

 but yet differs in several particulars from Bate's description. 

 The supraocular and hepatic spines ai-e well developed ; the 

 rostrum is almost as long as the e)'e stalks (the eyes not included), 

 with a short and fine dorsal spine at the base ; the eyes are nnieh 

 larger and the eye-stalks longer than in the stage described by 

 Kroyer and Bate. The third joint of the antenn. ped. is but a 

 little longer than the second, and the first one as long as the two 

 others taken together. The fourth to sixth abdominal segments each 

 with a very short and fine dorsal spine, the epimera of the first to 

 fourth segments each produced into a short spine, while this spine 

 is considerably longer on the epimera of the fifth segment; the 

 first segment besides on the side having a spine arising from the 

 anterior margin and directed forwards and outwards. On the 

 ext. br. of urp., which is almost seven times longer than broad, the 

 ciliated part occupies a little more than the half of the exterior 

 margin, which — as in almost all young larvse — is furnished with a 

 well-developed spine. 



Of S. corniculum, Kr., I have seen numerous specimens from the 

 Atlantic northward to lat. 42° N., from the Indian Ocean and 

 ranging into the Pacific to the Malelota Island and to lat. 16° 10' N., 

 long. 132° E. 



Whether the above-quoted S. lUrinqiiedens, Bate, may be a young 

 larva of S. corniculum, Kr., or of another species I am not able to 

 decide. 



S. longirostris. Bate (p. 415, pi. Ixxv. fig. 3). — Prof. 0. Chun 

 has determined the small stage of S. corniculum, Kr., just described 

 as S. longirostns. Bate, which is stated to be 6 mm. long and cap- 

 tured in " Mid Atlantic," and it is very possible that this determi- 

 nation may be correct ; but Bate's figure represents the oye-slallcs 

 and the rostrum a little too long,and especially a different proportion 

 between the joints of the antenn. ped. &c. I believe that it is 

 impossible to decide whether this identification is correct. 



Above I have further enumerated 5 species belonging to Group I. 

 Of these species S. pnccolhis, Bate (p. 423, pi. Ixxvii. fig. 2), is at 

 least rather nearly related to S. corniculum, Kr., from which it 

 seems to differ by a somewhat different shape of the ext. br. of urp. 

 and by having the fifth abdominal segment " dorsally produced to 

 a point." S. longicaudatus, Stimps. (p. 46), is a larva perhaps 

 belonging to the a»-ciict<s-group. On the three other species, all 

 larvae, I have no opinion. 



