1224 THE VOYAGE OF H.M.S. CHALLENGER. 



Ijreadth = 4 : 15. Thorax flatly conical, armed with denticulate spines. Meshes of lioth joints 

 irregular, polygonal, twice to six times as broad as the bars. Basal mouth armed with longer, 

 divergent, denticulate spines, 



Bimcnsion-s. — CeiDhalis O'Oo long, 0-04 broad ; thorax O'OG long, OlS broad. 



.Habitat. — North Pacific, Station 244, depth 2900 fathoms. 



3. AmpMplecta caUistoma, n. sp. (PL 59, fig. 2). 



Cephalis flat, cap-shaped, spiny, with obliterated collar stricture on the base ; its apical opening 

 -excentric, oblique, surrounded by a coronal of ten to twenty bristle-shaped spines. Length of the 

 •two joints = 4:5, breadth =: 7 : 25. Thorax flatly conical, armed with long bristle-shaped spines. 

 Meshes of both joints irregular, hexagonal, twice to six times as broad as the bars. Basal mouth 

 with a double irregular coronal of small square pores, and of bristle-shaped divergent spines. 



Dimensions — Cephalis 0-04 long, 0'07 broad ; thorax 0-05 long, 0-25 broad. 



Habitat. — Central Pacific, Station 271, surface. 



>Genus 548. Lychnocanium,^ Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. 



Berlin, p. 54. 



Definition. — S e t h o p i 1 i d a (vel Dicyrtida triradiata aperta), witli three solid 

 terminal feet on the peristome. No thoracic ribs. Cephalis with a horn. 



The gemis Lychnocanium, very rich i]i common living and fossil forms, comprises those 

 Sethopilida in which the thorax bears three simple terminal feet around the mouth, but 

 no lateral ribs in its wall. It has therefore been probably derived from Dictyojjhinms by 

 reduction and loss of these three lateral ribs. The mouth is commonly more or less 

 constricted. The three feet surrounding it are sometimes divergent, straight or curved, 

 at other times parallel and vertical, straight, or curved and convergent. The central 

 capsule exhibited in some living species, three or four distinct lobes, filling up the upper 

 half of the thorax. 



Subgenus 1. Lychnocanella, Haeckel. 



Definition. — Feet divergent, straight or scarcely curved ; their terminal distance 

 greater than their basal distance. 



1. Lychnocanium lanterna, n. sp. (PI. 61, fig. 7). 



Shell conical, rough, with slight collar stricture. Length of the two joints = 1:3, breadth = 

 1:3. Cephalis with a stout pyramidal horn of the same length. Thorax pear-shaped, twice as 



^ Lychnocanium = Lantern-basket ; ^is/x""?, '-■a^sou. 



