40 SUPPLEMENT TO THE 



mata, that I continue to maintain Linnc's and Sowcrby's species as distinct. Dr. 

 Kayser maintains A. desquavmta, Sow., A. Jlahellata, Goldf., A. latilinguis, Schnur, 

 and A. aspera, Schl., as named varieties of reticularis. 



29. Atrypa aspera, Schloth., sp. Dav., Dev. Mon., PI. X, fig. 5. 



A large Woolborough specimen of this species or variety, measuring eleven lines in 

 length by the same in breadth, and ornamented with some fifteen strong rounded ribs, 

 crossed by concentric foliaceous expansions about a line apart, was presented by Dr. 

 Battersby to the Torquay Natural History Museum. Prom its ribs rise strong tubular 

 spines two lines in length ; and in this respect and in general aspect it resembles the 

 Atrypa longispina of Bouchard, a form that occurs in the Upper Devonian at Perques, 

 near Boulogne, and which attains one inch and three quarters in length by the same in 

 breadth, and has spines projecting from its ribs half an inch in length. 



The resemblance between the Woolborough specimen above described and others 

 of A. longispina of equal dimensions is striking ; and the differences between these, 

 A. aspera and A. reticularis, are apparent. I have not myself seen any tubular spines, 

 similar to those observable in A. aspera and A. longispina^ projecting from the ribs of 

 A. reticularis proper, a form that occurs also at Perques in a perfect state of preservation. 



30. Atrypa? trigonella, Dav. Dev. Sup., PI. I, figs. 19, 19«, h. 



Shell subtrigonal, broadest anteriorly, with rounded angles, tapering posteriorly ; 

 ventral valve very gently convex; dorsal valve longitudinally grooved or depressed; 

 the ventral rather more convex than the dorsal valve, gently keeled ; beak small, slightly 

 incurved, and truncated by a circular foramen, separated from the hinge-margin by a 

 small deltidium in two pieces. Surface of valves irregularly marked by a small number 

 of comparatively largish, rounded, bifurcating ribs. 

 Length 5, width 4, depth 2 lines. 



Obs. — Nothing being known of the interior characters of this little species, it is provi- 

 sionally placed with Atrypa, from which it can be removed, if necessary, as soon as its 

 interior arrangements have been determined. In exterior shape and sculpture this small 

 species diSers from those known to me. It was found by Mr. G. P. Whidborne in the 

 Middle Devonian at Lummaton, near Torquay, where the shell seems to be exceedingly rare. 



