ART. 23 NEW PENTAMEROID BEACHIOPODS FROM ALASKA — KIBK 5 



complete individuals were collected, one of which was sectioned for 

 the study of internal structures. 



The type specimen has a maximum width of 31 mm., maximum 

 height of 25 mm., and a maximum depth of 18 mm. The hinge line 

 has an approximate length of 23 mm. The ornamentation consists 

 of fairly coarse longitudinal plications. 



The pedicle valve is convex in cross section but nearly straight 

 in longitudinal section. The result is to make this valve relatively 

 small and to give the species a reversed appearance, closely simulat- 

 ing the genus Broohdna with which the form is associated. The 

 beak is low, blunt, and everted. The delthyrium is short but un- 

 usually broad. The spondylium is shallow, as may be seen in the 

 figure. The delthyrium is bordered by narrow deltidial plates. The 

 cardinal areas are abruptly cut off from the remainder of the valve 

 and are almost flat. There is but a slight indication of a broad 

 median fold, and this is apparent only on the anterior margin. 



The grachial valve is uniformly convex. The beak is not promi- 

 nent but is strongly incurved. The anterior margin of the valve 

 is slightly sinuous, giving an indication of the presence of a median 

 depressed area that scarcely shows on the surface of the valve, 

 however. 



The brachial valve is uniformly convex. The beak is not promi- 

 the slight development of a sinus and fold on the brachial and 

 pedicle valves, its flattened pedicle valve, and the less elevated, 

 everted beak of the pedicle valve. 



The species was found associated with Brooksina alaskensis Kirk 

 at its type locality about one-fourth mile inland and about 3 miles 

 northeast of Edna Bay on the south side of Kosciusko Island, 

 Southeastern Alaska. Collector, Edwin Kirk. 



H olotype.— Cdii. No. 71037, U.S.N.M. 



EXPLANA'J^ION OF PLATE 



Figs. 1-4. CymUdium retrorsum, new species. Ventral, profile, dorsal, and 

 posterior views of the type specimen. 

 5-9. Cymhidium acutum, new si>ecies. Dorsal, ventral, posterior, pro- 

 file, and anterior views of the type specimen. 

 10-13. Cymbidium acutum, new species. 



10. Section of brachial valve showing septa and inclined crural 



processes. The latter are somewhat thickened and 

 obscured by secondary deposits, x 3. 



11. Section of pedicle valve near the apex, showing the shal- 



low unsupported spondylium. x 3. 



12. Section of pedicle valve anterior to fig. 11. x 3. 



13. Section of pedicle valve still farther forward, x 3. 



o 



