1322 THE VOYAGE Of H.M.S. CHALLENGEE. 



1. Tlieopilumi tricostatwn, n. sp. (PL 70, fig. 6). 



Shell flatly conical, smooth. Length of the three joints = 1:4:2, breadth = 2 : 6 : 10. Cephalis 

 subspherical, with a thin oblique horn of the same length. Thorax with three stout ribs in its wall, 

 and with subregular, hexagonal pores increasing in size towards the girdle. Abdomen flatter than 

 the thorax, without ribs, nearly horizontal, with subregular, square pores, disposed in four to six 

 concentric, subcircular series of different sizes ; decreasing in size towards the wide open moutli. 

 Seen from the side, this species resembles Corocalyptra agnesw, (PL 59, fig. o). 



J)i7)iensions. — Length of the three joints, a 0-02, b O'OS, c 0-04 ; breadth, a 0-03, b 0-12, c 0-2. 



SabitaL-^Central Pacific, Stations 260 to 274, surface. 



2. Theopilium triradiatum, n. sp. 



Shell flatly conical, smooth, in general of the same form as, and with similar fenestration to, the 

 preceding species, but different in the proportions. Length of the three joints = 1:4:2, breadth = 

 2:4:6. Cephalis hemispherical, with two divergent, thin horns of the same length. Thorax more 

 elevated, al:iout as high as broad. The three divergent ribs are not limited to the thorax, but pro- 

 longed through the whole abdomen, the outline of which is a prolongation of that of the thorax. 



Dimensions. — Length of the three joints, a 0"025, b O'l, r 0'05 ; breadth, n 0-05, b 01, c 0'15. 



Habitat. — Tropical Atlantic, Station 347, surface. 



3. Theopilium cranoides, HaeckeL 



£ucijrtidiu7n cranoides, Haeckel, 1862, Monogr. d. Eadiol., p. 320, Taf. vii. figs. 1-3. 



Shell campanulate-conical, smooth. Length of the three joints = 2:5:4, breadth = 3:9:10. 

 Cephalis ovate, with a straight, excentric, prLsmatic horn of the same length. The campanulate 

 thorax is separated from it by no external collar stricture, but by an internal septum. From the 

 base of the horn arise three divergent radial ribs, running in the wall of the two first joints to the 

 lumbar stricture (loc. cit., TaL vii. fig. 3). Abdomen short and wide, without ribs. Pores rather 

 large, regular, circular, quincuncial, in the cephalis smaller. Central capsule four-lobed. 



Dimensions. — -Length of the three joints, a 0-027, b 0-054, c 0-047 ; breadth, a 0-03, b 0-09, 

 c 0-1. 



Habitat. — Mediterranean (Messina), surface. 



Genus 584. Corocalyptra,^ n. gen. 



Definition. — T h e o p i 1 i d a (vel Tricyrtida triradiata aperta) with three simple, 

 free, lateral wings, arising from the collar stricture bet-ween cephalis and thorax. 



The genus Corocalyptra comprises a small number of very elegant hat-shaped 

 Tricyrtida, which resemble greatly Eucecryphalus among the Dicyrtida. As in the 



1 Corocalyptra = Co\i or hood of a girl ; xo^yi, xaAt^r/a. 



