LOPHOBRANCHII. 29 



more than twice as short as the head and body together. 

 Body encircled by yellow and violet-brown rings. 



Descr. — Body very long, cylindrico-heptagonal anteriorly, 

 tetragonal posteriorly, and having a breadth equal to its height, 

 or to the 30th or 31st part of its length. Head measuring 

 about one-fifth of the length of the body, while the diameter 

 of the eve is about the 8th or 85th part of the length of the 

 head. The rostro-frontal profile is concave before the eyes ; and 

 the snout is about thrice as long as the post-ocular part of the 

 head ; it is compressed, and seven or eight times larger than its 

 slenderest part is high. Forehead and convex crown of the head 

 granular ; no medial post-ocular crests. A short crest on each 

 side of the snout, and together with the orbits slightly denticu- 

 lated. Gill-cover granular, the grains being disposed somewhat 

 in rows. Body-rings 18, tail-rings 20, the individual rings slightly 

 granular ; the interstitial plates small, oval, and also slightly 

 granular ; the keels of the several rings very low, but emitting 

 a very conspicuous little spine pointing backwards from each 

 ring. The small spines of the medial ventral keel are shorter 

 than those of the other keels. The tail, excluding its fin, is a 

 little shorter than the trunk of the body, and twice as short as 

 the trunk and head together. Dorsal fin commencing above the 

 anus on the 18th body-ring, and ending on the 4th tail-ring. 

 It is lower than the body : the anal is very diminutive, and the 

 oblong obtuse caudal fin is about twice as long as the post-ocular 

 portion of the head. Colour of the body beautifully yellow, 

 encircled by 2/ violet-brown rings broader than the intermediate 

 spaces. On the snout there are 5 rings, one of them passing 

 through the eyes, 2 between the eyes and the pectoral fin, and 

 9 between the pectoral and anal fins; while the remainder belong 

 to the tail. The fins are rosaceous, the caudal alone being red- 

 dish-violet. 



Rad.—T). 26 ; P. 21 or 22 ; A. 4 ; C. 9. Length of specimens 

 5*1 and Scinches. 



Found at Batavia in the sea near the Onrust Island. 



Genus 4. ICHTHY0CA1OUS, Kp. 



Diagn. — The edges of the concave back coalesce with those 

 of the tail into one line, which runs without interruption to 

 the caudal fin. 



Descr. — Head short, with a shorter, compressed, sharp-ridged 

 snout. Orbits slightly projecting. Operculum round, swollen, 

 higher than broad, and grained like the head. Tail almost as 



