952 dh. h. j. Hansen on ceustacbans [Dec. 1, 



the 2 branchiaa above trl.' are well developed ; the statements of 

 earlier authors on the branchise of this species are rather 

 deficient. 



As stated above, S. ancylops, Kr. (p. 262, tab. iii. fig. 8,n-e), is 

 the Mastigoints of >S'. atlanticus, and I have seen every stage of 

 transition between the larva and the adult. S. ovatocidus, J5uto 

 (p. 408, pi. Ixxiv. fig. 2), is a stage a little older than that 

 described as S. ancylops by Kroyer and Bate. 



The stages from 7 mm. in length and more are easily dis- 

 tinguished from all other known larvae by the shape of the eyes, of 

 which Kroyer has given two good figures, and also in the still 

 younger stages mentioned below the eyes have a rather similar 

 shape ; in the older stages the sixth joint of mxp.^ shows the same 

 subdivision into 6 joints as is found in the adult. 



A small specimen examined by me is scarcely 6-5 mm. long, trl.* 

 is even shorter than the two proximal joints of trl.' together ; the 

 eyes and the eye-stalks are longer than in the stage figured by 

 Kroyer, reaching a little beyond the basis of the third joint of the 

 antenn. ped. ; the first joint of this peduncle is about -^^ longer 

 than the third ; the very long and slender rostrum occupies f of 

 the length of the eye-stalks and carries a small dorsal spine over 

 its basis ; the inferior side of the abdominal segments is without 

 spines, while a rudiment of a spine is present on the dorsal side 

 of the third segment, and the spines on the fourth and fifth 

 segments are a little longer than in the following stage ; the 

 ciliated part of the ext. br. of urp. occupies a little more than |, 

 but not g of the exterior margin. 



The smallest specimen examined by me is but 3-5 mm. long, 

 without the rostrum ; the eye-stalks are extremely long, together 

 with the eyes almost as long as the carapace in the median line ; 

 the rostrum reaches almost to the tip of the eyes and is adorned 

 with a shorter dorsal spine at the basis and with some short settc 

 on the distal part ; the supra-orbital and the hepatic spines are 

 considerably elongated. The dorsal spine on the third abdominal 

 segment is rather long, the spines on the fourth and fifth segments 

 very long ; the epimera of the 5 anterior segments are each 

 produced into a fine spine bent somewhat outwards ; the spine on 

 the ext. br. of urp. is placed almost before the middle of the 

 exterior margin, and the branch itself is extremely slender, 13 or 

 14 times longer than broad. This stage, thus rather diverging 

 from the older ones, is, in my opinion, the youngest Maslujoims, 

 and was taken by Prof. Chun at the Canary Islands. 



Of S. atlanticus I have seen specimens from the Atlantic, north- 

 ward to lat. 42° N., from the Indian Ocean and from the Pacific 

 lat. 15° S., long. 109° 20' E., and the China Sea. 



S. cornutus, Kr. (p. 249, tab. ii. fig. 2, a-l). This species is 

 easily distinguished from S. atlanticus, M.-Edw., by the following 

 characters: — The rostrum is ranch longer, directed obliquely 

 forwards and slenderly acuminated, the eyes are smaller, the 

 third joint of the antenn. ped. is distinctly longer than the first, 



