70 AMERICAN JOURNAL 



in regard to Rhynchonella loxia, F. de W., the type of the genus. 

 Although referred by JBronn and Herrmannsen to Spirifer cus- 

 pidatus ! it appears to be allied to R. acuta and other Liassic 

 species, and is from the Jurassic formation near Moscow. 



The name Stenocisma has been proposed for certain fossil 

 Rhynchonellce of the older rocks, on the ground that they differ 

 from the recent species and from the R. loxia. The latter sup- 

 position would appear to have little foundation, but cannot be 

 decided until the interior of R. loxia is worked out. It is much 

 more likely that, if differences exist, they should be between the 

 R. loxia and the recent forms, and that R. loxia should agree 

 with the older fossil species. In this case a new name would be 

 required only for the recent forms, for which the name Hemithy- 

 ri8, proposed by D'Orbigny for R. psittacea, would have to be 

 used. The value of the differences, so far established, does not 

 appear to be very great. 



Add to the list of recent species (p. 153), R. sicula, Sequenza, 

 Davidson, Mon. Italian Tertiary Brachiopods, ii, p. 23, PI. xx, 

 f. 6, 1870. Hab. Fossil in the Pliocene at Messina ; recent off 

 the coast of Portugal. Jeffreys. 



Geuus DIMERELLA, Zittel. 



Dimerella, Zittel, Dunker and Von Meyer's Paleontographica, 

 Aug. 1870, p. 220. 



Shell small, Rhynchonelloid, impunctate, with a large foramen. 

 Neural valve with an entire edge, without a septum. Hremal 

 valve with a large, very prominent septum, which divides the 

 cavity of the shell, when closed, into two chambers ; with two 

 stout, diverging, hook-shaped crura as in Rhynchonella. 



Type D. Giimbeli, Zittel, 1. cit. p. 222, PI. xli, figs. 27—30. 

 Aug. 1870. 



In December (2d) 1869, Mr. J. Gwyn Jeffreys, F. R. S., pub- 

 lished in "Nature" of that date, p. 136, the following remarks. 

 "Among the mollusca were valves of an imperforate Brachiopod 

 with a septum in the lower valve, which I propose to name 

 Cryptopora gnomon." 



For some reason not stated, Mr. Jeffreys adopted a second 

 name in his subsequent publications, and in the Preliminary Re- 

 port of the Porcupine Expedition for 1869 (No. 121 of the Proc. 

 Roy. Soc.) he states, " among the mollusca were valves of an 

 imperforate Brachiopod, with a septum in the lower valve, which 

 we propose to name Atretia gnomon." (^[ 36, p. 421.) I have 

 not seen specimens of either Dimerella or Atretia, but in a late 

 communication, Mr. Jeffreys remarks, in regard to Dimerella 



