1180 THE VOYAGE OF H.M.S. CHALLENGER. 



Subfamily 1. ARCHICORIDA, Haeckel, 1881, Prodromus, p. 427. 



Definition. C yrtocalpida, with the basal mouth of the shell open (vel Mono- 

 cyrtida eradiata aperta). 



Genus 526. Cornutella, 1 Ehrenberg, 1838, Abhandl. d. k. Akad. 

 d. Wiss. Berlin, p. 128. 



Definition. A rchicorida with conical shell, gradually dilated towards the wide 

 open mouth. Apex armed with a horn. 



The genus Cornutella is one of the three oldest genera of Polycystina, described 

 by Ehrenberg, in 1838 (Cornutella, Lithocampe, and Haliomma). He afterwards 

 enumerated, in 1872 and 1875, a large number of fossil and living species, the majority 

 of which, however, belong to other genera of Monocyrtida and Dicyrtida (at least six 

 or seven different genera). We retain here as the true type of the genus the oldest 

 known species: Cornutella clathrata, and the nearly allied forms Cornutella stylo- 

 phcena, Cornutella mitra, Cornutella circularis, &c. The simple conical shell exhibits 

 no distinct trace of an original cephalis, excepting the apical horn; it may have origin- 

 ated either independently, or been derived from Sethoconus, by loss of the cephalis. 



Subgenus 1. Cornutellium, Haeckel. 



Definition. Axis of the conical shell straight. Pores polygonal, or roundish with 

 polygonal frames. 



1. Cornutella hexagona, n. sp. (PL 54, fig. 9). 



Shell slender, conical, with straight outlines. Pores subregular, hexagonal, gradually increasing 

 in size towards the mouth ; in about ten to twelve longitudinal series, in the upper part very small. 

 Horn slenderly conical, nearly bristle-shaped, long. 



Dimensions. Shell 01 to 015 long, 0'04 to 0'06 broad. 



Habitat. Central Pacific, Stations 265 to 274, surface, and at different depths. 



2. Cornutella sethoconus, n. sp. (PI. 54, fig. 10). 



Shell slender, conical, with undulate outlines. Pores subregular, hexagonal, gradually increasing 

 in size towards the mouth, in about fifteen to eighteen longitudinal series, in the upper part circular. 

 Horn small, conical, short. The network is not so delicate as in the preceding similar species. 



Dimensions. Shell 012 to 016 long, 0'06 to 0'08 broad. 



Habitat. South Atlantic, Station 332, depth 2200 fathoms. 



1 Cornutella = Small horn ; diminutive of cornu. 



