1108 THE VOYAGE OF H.M.S. CHALLENGER. 



be advisable to distinguish a number of genera according to the diflferent number of the 

 porous tubes and of the lobes of the cephalis. The base of the latter is constantly- 

 closed by a basal lattice-plate, and usually exhibits two or three pairs of cortinar pores, 

 identical with those of the Semantida. 



The phylogenetic origin of the Cannobotryida may be found either in the 

 Zygospyrida or in the Monocyrtida ; they differ from these two similar groups in the 

 lobation of the cephalis, which is effected by the development of internal septa and 

 external constrictions. 



Synopsis of the Genera of Cannobotryida. 

 Cephalis without porous tubes, ....... 486. Botryopera. 



Cephalis with a variable number of porous tubes, ..... 487. Cannobotrys. 



Genus 486. Botryopera,^ n. gen. 



Definition. — C a n n o b o t r y i d a without tubes on the cephalis. 



The genus Botryopera is the simplest form among the Botryodea, the shell con- 

 sisting of a lobate cephalis only, without tubes or radial appendages. It may be derived 

 either from Dictyosp>yris or from Archicapsa by development of the horizontal fold in the 

 frontal face of the shell, and the corresponding internal frontal septum, which separates the 

 larger occipital lobe from the smaller facial half ; the latter may be divided again into 

 paired frontal lobes, lateral buccal lobes, &c. Botryopera may be the common ancestral 

 form of many Botryodea. 



1. Botryopera cyrtoloba, n. sp. (PI. 96, fig. l). 



Cephalis trilobate ; the posterior odd occipital lobe helmet-shaped, about twice as large as the 

 two paii'ed anterior frontal lobes, which are subovate and covered by the upper half of the former. 

 Pores small and numerous, subregular, circular ; some larger pores at the base. 



DimeTisions. — Length of the shell 0'08, basal breadth 0'06. 



Habitat. — Central Pacific, Station 265 to 274, depth 2350 to 2925 fathoms. 



2. Botryopera triloba, Haeckel. 



Lithohotrys triloba, Ehrenberg, 1854, Mikrogeol., Taf. xxii. tig. 30. 



Cephalis trilobate ; the occipital lobe subcylindrical, one and a half times as long as the two 

 frontal lobes, which are slender, ovate and not covered by the former. Pores small and numerous. 

 Dimensions. — Length of the shell 0-05, breadth O'OS. 



Habitat. — Fossil in Tertiary rocks of the Mediterranean (Sicily, Greece, &c.) 



' Boirj/opera = Basket with grapes ; fiir^vi, Trti^x. 



