BRITISH DEVONIAN BRACHIOPODA. 



44. Skenidium areola, Quensfedt, sp. ? Dav., Dev. Sup., PI. Ill, figs. 11 to 14. 



Okthis akeola, Quenstedt. Brachiopod, p. 589, and Atlas, tab. 57, fig. 27, 1871- 

 Mystrophora areola, E. Kayser. Die Brachiopoden des Mittel- und Ober-Devon. 



der Eifel, Zeitschr. Deutscben Geol. Gesellscbaft 

 fur 1871, p. 612, tab. xiii, fig. 5, 1871. 



Shell small, subpentagonal, wider than long, anteriorly rounded and indented in 

 front ; hinge-line a little shorter than the breadth of the shell ; dorsal valve very gently 

 convex, with a deepish median longitudinal depression, commencing at the umbo, and 

 widening and deepening as it nears the front ; hinge-area narrow ; ventral much more 

 convex and deeper than the dorsal valve, somewhat longitudinally keeled ; beak very 

 slightly incurved ; area large, triangular, bent backwards at an obtuse angle to the plane 

 of the dorsal valve, and divided by a fissure partially arched over by a pseudo-deltidium. 

 Surface of valves covered with small radiating riblets, numerous, with one or two shorter 

 ones here and there interpolated between the larger pairs. In the interior of the dorsal 

 valve, under the cardinal process, extends a large triangular median plate or septum, 

 extending throughout the length of the shell, and dividing it into two chambers. Hinge- 

 plate large, saucer-shaped, and extending to nearly half the length of the septum, to the 

 upper portion of which it is attached (see Sup., PI. Ill, fig. 13). 



Length 3, width 3J, depth nearly 2 lines. 



A specimen from the Eifel measured — length 5, width 6, depth 3 lines. 

 Obs. — When Mr. Whidborne sent me the specimen under description, which he had 

 found in the Middle-Devonian Limestone at Lummaton, near Torquay, I was at once 

 struck with its resemblance to the Mystroiihora areola of Kayser. In order to be certain, 

 I forwarded drawings of our English specimen to Dr. Kayser, and in answer he says, " I 

 have no doubt that it is my M. areola. In the Eifel it occurs in the Crinoid bod, which 

 constitutes the base of the upper part of the Middle Devonian, i.e. the Stringocephalus 

 Limestone." He likewise kindly sent me typical examples of the Eifel species. 

 They were similar to those found by Mr. Whidborne at Lummaton, only larger 

 or more developed individuals. From Dr. Kayser's figure I had been led to suppose 

 that the ribs were simple and of equal width, but the specimen sent to me by Dr. 

 Kayser showed that the ribbing is exactly similar to that observed on our English 

 specimens, one or two smaller ribs being interpolated between the larger ones. I am 

 likewise indebted to Prof. Dewalque for specimens from Nimes, in Belgium. Skenidium 

 areola occurs also in a similar bed and position at Lummaton. It bears a resemblance to 

 the Skenidium ( Or this) Leioisii of our Wenlock limestone and shales ; and this resemblance 

 did not escape Dr. Kayser's observing eye, for he alludes to the fact at p. 614 of his 

 work on the ' Brachiopoda of the Eifel/ and describes and figures my Silurian species with 



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