4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. QI 



^Furthermore, the ribs are sharper and narrower than those of A. 

 johnsoni. The feature of an intercalated rib between the two median 

 costae marking the fold is shared by both species, but in addition to 

 the median intercalated rib, there are extra costae inserted between 

 the primary costae along the front margin of A. harrettiana. 



Internally there are differences between A. harrettiana and A. 

 johnsoni in the loop and apical region of the ventral valve. The 

 loop of A. johnsoni meets the floor of the valve farther forward than 

 in A. harrettiana. In the ventral valve of the latter the pedicle 

 collar is less elevated and less strongly developed than in A. johnsoni. 

 There are equally as strong color and ribbing differences between 

 A. johnsoni and A. lutea Dall as there are between the new species 

 and A. harrettiana. The common color of A. lutea is a pale yellow, 

 which is in contrast to the salmon color of A. johnsoni. The ribbing 

 pattern of A. lutea is characterized by a rather prominent median 

 sinus on both valves and frequent intercalation of ribs. There are 

 also differences internally between the two species. The septum of 

 A. lutea is serrate along its front margin, but that of A. johnsoni 

 forms a somewhat sigmoidal curve in profile. 



EXPLANATION OF PLATES 

 Plate i 



All views are of the holotype, U.S.N.M. no. 431002. 



Figs. 1-8. Gryphus bartschi Cooper, n. sp. Fig. i, posterior view showing 

 labiate foramen, X 2. Fig. 2, lateral view, X 2. Fig. 3, anterior 

 view, commissure rectimarginate, X 2. Fig. 4, ventral view, X 2. 

 Fig. 5, dorsal view, X 2. Fig. 6, dorsal view, natural size. Fig. 7, 

 posterior view of ventral valve showing symphytium and foramen, 

 X 4- Fig. 8, dorsal interior showing narrow loop with plicated 

 transverse ribbon. 



Fig. 9. Gryphus cubensis (Pourtales). Dorsal view of a characteristic specimen 

 introduced for comparison with G. bartschi, X 2. Note the marked 

 triangular outline of G. cubensis as compared with the oval outline 

 of G. bartschi. U.S.N.M. no. 334762. 



Fig. id. Argyrothcca johnsoni Cooper, n. sp. Anterior view of a young specimen 

 attached to a fragment of bryozoan colony. Note the broadly sul- 

 cate anterior commissure, median intercalated rib, and great width 

 of the shell, X 4- Paratype, U.S.N.M. no. 43ioo3f. 



Plate 2 



Argyrothcca johnsoni Cooper, n. sp. 



Figs, i, 2. Ventral and dorsal views respectively of the holotype, natural size. 

 U.S.N.M. no. 431003. 



I 



