1452 THE VOYAGE OF H.M.S. CHALLENGER. 



Genus 635. Artopera,^ Haeckel, 1881, Prodromus, p. 438. 



Definition. — S t i c h o p e r i d a witli three solid lateral ribs or wings, and with a 

 vertical basal spine on the end of the pointed last joint. Cephalis with a horn. 



The genus Artopera differs from its ancestral genus, Stichopera, in the development of 

 a vertical terminal spine on the end of the last joint, and bears therefore to it the same 

 relation that Rhopalatractus exhibits to Rhopalocanium among the Tricyrtida. 



1. Artopera loxia, Haeckel. 



Lithornithium loxia, Ehrenberg, 1854, Mikrogeol., Taf. xxsvi. fig. 8; Abhandl. d. k. Akad. d. 

 Wiss. Berlin, 1875, p. 78, Taf. iv. fig. 8. 



Shell spindle-shaped, with three deep strictures. Length of the four joints = 2:5:5:4. 

 Cephalis subspherical, hyaline, without pores, with a thick conical horn of the same length. From 

 the two following joints, which are nearly equal in size and of eampanulate form, arise, with broad 

 base, three divergent, slender, triangular wings. The fourth joint is smaller, inversely conical, and 

 bears on the basal pole a strong, three-sided pyramidal, vertical spine, half as long as the shell. 

 Pores subregular, circular. 



Dimensions. — Length of the shell (with four joints) 0'18, breadth 0'07. Length of the single 

 joints, a 0-02, h 0-055, c 0-055, d 0-05. 



HaMtat. — Fossil in Barbados. 



2. Artopera motacilla, n. sp. 



Shell spindle-shaped, with three distinct strictiires. Length of the four joints = 1:2:3:2. 

 Cephahs subspherical, with a conical horn of twice the length. From the second jomt arise three 

 longitudinal, smooth, divergent ribs, which are prolonged over the third joint, and terminate at the 

 third stricture in three short, conical teeth. The fourth is inversely conical, and bears on the 

 basal pole a strong, vertical, cylindrical spine, nearly half as long as the shell. Pores subregular, 

 circular, hexagonaUy framed. (Similar to Rhopalatractus pentacanthus, PI. 68, fig. 11, but differing 

 in the presence of three sharp strictures, and a large, conical, basal joint). 



Dimensions. — Length of the shell (with four joints) O'lS. Breadth of third (broadest) joint O'OO. 

 Length of the single joint, a 0-02, h 0-04, c 0-06, d 0-04. 



Habitat. — Western Tropical Pacific (Phihppine Sea), Station 198, depth 2150 fathoms. 



3. Artopera fusiformis, n. sp. 



Shell spindle-shaped, with three distinct strictures. Length of the four joints = 2:3:5:5. 

 Cephalis conical, with a strong, conical horn of the same length. Along the three first joints arise 



' .Artopera = Bread-pouch; aigroj, 9r^;«. 



