ORTMANN I TERTIARY INVERTEBRATES. 



Remarks: v. Ihering distinguishes two species, C. alta and dalli, which 

 I believe to be identical : in order to support my opinion, I give here 

 detailed measurements of 14 good specimens out of our material (Nos. i, 

 2, 4, 9-14 from Santa Cruz, Nos. 3, 5-8 from Mt. of Observation). 



In 1897, v - Ihering mentioned as distinctive characters betwen C. mul- 

 ticostata and dalli the following: (i) External form, (2) sculpture of shell, 

 (3) number of sulci of the area, (4) size. In 1899 ne modified his state- 

 ments as to the third character : he says that a shell of C. alta (which he 

 unites with C. mttlticostatd] of 45 mm length has an area 7 mm broad, 

 with 9 sulci, while C. dalli at a length of 50 mm has an area 5 mm broad, 

 and only two sulci. This looks certainly like a striking difference. His 

 C. multicostata ( = alta) of 1897 i s 3^ mm. long, and has only two sulci. 



Among our specimens, one (No. 2), of the same size (50 mm) as the 

 individual of C. dalli just mentioned, has only 3 sulci, and this number 

 hardly increases in the specimens Nos. 3-8 (length from 64 to 71 mm): 

 there are only 3 to 5 sulci, and specimens Nos. 10 and 1 1 (length 79 and 

 80 mm) continue this series regularly with from 5 to 6 sulci. 



But No. 9 is outside of the series ; its size is hardly larger than that of 

 No. 8, but the sulci of the area number 6, or 7. Although this specimen 

 must still be classed with v. Ihering's C. dalli, it shows clearly that some- 

 times in individuals of comparatively smaller size the number of sulci may 

 be exceptionally high. On the other hand, we see in No. 14, that in 

 comparatively large individuals the number of sulci may remain very small 



