A FOSSIL MARINE DIATOMACEOUS DEPOSIT. 143 



A, undulatus, Ehr. — Small forms of this occur with extreme 

 rarity. 



A. (undulatus, Ehr. var.?) constrictus, n. sp., Gr. and St. — Valve 

 with three undulations and three distinct processes. In the margin 

 of the valve there is a constriction of the inner edge of the margin 

 at the end of each of the rays, which gives to the form a very 

 distinct appearance. The compartments are more sparsely cellulose 

 than is the case in A. undulatus, Ehr. Diam. -0033." (PI. XIV, 

 Fig. 63.) 



A. simbirskianus, A. Sch. — An example of this has occurred. 



Porodiscus hirsutus, n. sp., Gr. and St. — Valve, with clear cir- 

 cular central space, about i of the total diameter, the remainder of 

 the surface being covered with papilla which are very much coarser 

 than in P. interrvptus, and are not interrupted near the margin as 

 in that species. Diam. -0027". (PL XIV, Fig. 54.) 



Asierolampra uraster, n. sp., Gr. and St. — Valve rather coarsely 

 reticulated, the interior extremities of the cellular compartments 

 angular with slightly rounded ends. Centre, of a few large cells, 

 connected by a radial line with the apex of each compartment. It 

 will be observed that in the specimen figured, which is the only one 

 observed, there are two radial lines connecting one of the compart- 

 ments with the central cells. This is probably abnormal. 



The clear spaces between the compartments are broad and taper- 

 ing, ending considerably within the margin, and showing at the 

 termination of each an indentation (possibly a spine ?). We are 

 indebted for the only specimen of this species to Dr. Gray. 

 (PI. XIII, Fig. 42.) 



Anaulus ? subconstrictus, Gr. and St. — We place this singular 

 form here for the present with some hesitation. 



Valve narrow with slightly expanded ovate ends, which are 

 separated from the central portion by distinct septa. Surface 

 covered with dots, which in the centre are arranged radially. In 

 frastular view, the valve, is very slightly constricted and has rounded 

 ends. On the ventral side, at each end of the valve, there is 

 apparently a folding over of the membrane or cell wall partly 

 closing the interior. Length '0045'. (PI. XIV, Figs. 59, 60.) 



Hemiaulus dissimilis, n. sp., Gr. and St. — In this form the con- 

 tiguous valves are dissimilar. We figure a frustule, one of several 

 which have occurred to us, from which it will be seen that one 

 valve resembles that of Hemiaulus, with the usual processes or 



