28 



CARBONIFEROUS ENTOMOSTRACA. 



carapace, semicircular above in outline, elliptical behind, almost straight below, and flat 

 enough to stand on its ventral face. Its antero-ventral margin is produced, prow-like ; 

 the sinus is broadly curved, but the beak has been much reduced by fracture in fig. 5 a. 

 Rather above the middle of the posterior margin is the round spot, formed by a small 

 indentation in the edge of each valve, with its central core of stone, and corresponding 

 with the base of a hollow conical process, formed of two more or less terete and approxi- 

 mate spines, such as we see in several Oypridinads ; for instance, Thilomedes interpuncta. 

 Edge-view pyriform; end-view suborbicular, with a tendency towards hexagonal. 



Portions of the eroded shell remain on the dorsal and ventral regions (fig. 5 a), and 

 we can see evidence of a small inturned flange on the ventral edges, with a minutely 

 crenulate parallel edging or border (not clearly shown in the figures) . There is also 

 clearly discernible a low hump in each antero-dorsal region, affecting the end-profile of 

 the carapace, and somewhat below it is a roughness at about the usual position of the 

 muscle-spot. 



This specimen has the same proportions as fig. 4 ; it is more rotund than fig. 21 : 

 excepting that its tubercle is not so strongly pronounced, and its posterior spine was 

 higher up than in fig. 21, and lower than in fig. 4, we see no essential difference between 

 them. 



Eig. 4. Length \ ; height \ ; thickness^g inch. Proportions 11 



Eig. 21. „ 3^; j> 9^; ■,, 4 >, 17 



The figured specimens of Cypridellina Burrovii are from the Lower Scar Limestone of 

 Settle, Yorkshire ; collected by Mr. J. H. Burrow, M.A., who has worked the district 

 geologically with great success, and has favoured us with the use of his extensive collec- 

 tion. We have, therefore, adopted his name for this characteristic and wide-spread 

 species. 



8 



8. 



11 



: 11. 



101 



11. 



2.* Cypridellina Burrovii, Var. Longnoriensis, nov. Plate III, fig. 8. 



Carapace gibbose, suborbicular, varying in the curve of back and hind quarters ; 

 notched and produced in front with somewhat variable contours, fig. 8 being an average 

 form. Tubercle small, low down, and forward; sometimes scarcely perceptible. 



Length ^ ; height \ ; thickness ^ inch. Proportions 8 : 6| : 5. 



This small and weak Cypridellina, gregarious in the Derbyshire limestone, presents 

 strong characters of alliance with the large C. Burrovii above described, and must be 

 taken for a local variety of the species. 



Accompanied by Aviculopecten and some small shells, it constitutes a mass of grey 

 Carboniferous Limestone, from Longnor, Derbyshire : Tablet ff in the Museum of 

 the Geological Survey, London (Geol. Survey Map, Sheet 81, S.E.). 



