[burwash] new species OF MARINE INVERTEBRATES 81 



(Tetrabranchiata) . 



Haploceras churchi (sp. nov.) 



(Plate I, Fig. 2) 



This species is represented by about a third of the outer vohition 

 without the aperture. The shell is obliquely compressed laterally, 

 rounded on the venter and dorsally impressed. The height, measured 

 from the venter to the umbilical edge is slightly greater than the width, 

 but slightly less if measured from the venter to the center of the dorsal 

 furrow. The sutures are not shown. The surface is smooth, but crossed 

 by about nine rounded costse in each volution, each of which has a groove- 

 like constriction of the shell on each side of it. The costse pass directly 

 across the venter and down the sides for some distance, but are bent 

 backward as they approach the umbilical edge. The greatest width 

 is near the umbilical edge, which is rounded. 



This species differs from Des7noceras planulatum (Sowerby) in the 

 absence of ribs in the wider intervals between the constrictions. 



Gasteropoda. 



Turritella tricarinata (sp. nov.). 



(Plate I, Fig. 3) 



The specimen described is partially embedded in the matrix. It 

 has a total length of about 9 mm., and consists of eight whorls. The 

 apical angle is about 14°. The interior casts of the whorls show a flat 

 upper surface projecting outward from the suture to a narrowly rounded 

 shoulder, from which the upper middle part of the whorl descends 

 parallel to the axis to about the middle line of the whorl, when it 

 slants inwards with a slightly convex surface from a second shoulder 

 to the suture at the base of the whorl. In the younger whorls the 

 shoulders are not so distinct, and the profile from the upper suture to 

 the lower in each whorl is that of an ogee curve, of which the upper half 

 has the larger and the lower a smaller radius. The revolving ridges 

 which distinguish the outer surface of the shell can be seen only on part 

 of the body whorl, where some of the shell remains. They are three 

 in number, one on the upper and one on the median shoulder, and one, 

 less distinctly seen, on the basal slope of the whorl. Nothing can be 

 seen of the aperture, nor of the uml)ilicus, and it is therefore impossible 

 to assign this species to its appropriate sub-genus. 



