146 PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 



found there, v. Ihering says himself (1899, p. 43) that this identification 

 is doubtful. But the presence of this species in the Cape Fairweather beds 

 affords some support to v. Ihering's original opinion. 



Affinities: As v. Ihering points out, this species is very closely allied 

 to Artemis foncferosn Gray (see: Philippi, 1887, p. 113, pi. 14, f. 5, and 

 Moerickc, 1896, p. 585), which is found in the Pliocene Coquimbo beds 

 of Chili, and living on the western coast of Mexico. The latter form, 

 however, is larger, and the concentric sculpture is less marked in the 

 middle of the shell. The hinge agrees closely in both species, and even 

 the lunula, although there is a slight difference as v. Ihering points out, 

 is almost the same, and differs from other species of Dosiuia. 



D. ponderosa is represented in the Miocene deposits of California by 

 D. matlicwsoni Gabb (1869, p. 57, pi. 15, f. 16), which differs from D. 

 meriditmalis in the more swollen form, but agrees well in size. 



A very close resemblance exists also to D. acctnbnlnin (Conr.). Al- 

 though, in comparing the figure given by Whitfield (1894, pi. 13, f. 2), 

 and copied from Conrad, this resemblance is not so very striking as regards 

 the sculpture, I have compared specimens from Virginia, in which the 

 sculpture is essentially identical. The only difference is the large size, 

 and the less excavated lunular margin of D. acetabnlum. D. acetabiiliuu 

 is from the Miocene of the Atlantic coast of N. America. 



D. denselineata Pritchard (1896, p. 135, pi. 4, f. 5-7) seems to be closely 

 allied to D. meridionalis, especially in sculpture, but the outline is dif- 

 ferent : the posterior dorsal margin appears longer, and forms a more dis- 

 tinct angle posteriorly. It is from Table Cape, Tasmania and Spring- 

 Creek, Victoria. 



Thus the presence of this comparatively large and typical Dosinia in 

 the Patagonian beds points clearly to a Neogene age, and this view is 

 still- more supported by the fact, that D. meridionalis is apparently closely 

 related to, and perhaps the ancestral form of a species that is still found 

 living on the western coast of America. Probably all the forms mentioned 

 above are connected genetically. 



