10 



THE NAUTILUS. 



E. dilatatus 



fjength Height Diameter 



130 mm. 60 mm. 35 mm. 



86 mm. 41 mm. 24 mm. 



.30 mm. 16 mm. 7 mm. 



Var. sterkii 

 Length Height Diameter 



87 mm. 46 mm. 28 mjn. 

 59 mm. 31 mm. 18 mm. 

 26 mm. 13 mm. 7 mm. 



Factors obtained from above by comparison of length with 

 height and diameter show that greater height and inflation 

 rest with sterkii — 51 ^J and 309; as against 48% and 25%. 

 [n variety sterkii, the average distance of the beaks from the 

 anterior extremity of the shell is 18% of the total length ; in 

 dilatatus this is 25%. There appears to be no substantial 

 difference between values obtained with Simpson's measure- 

 ments and my own. 



This new variety is respectfully dedicated to Dr. V. C. 

 Sterki, who first commented upon the distinction between it 

 and the stream forms. (4) Type no. 61. 4268, card catalogue 

 Carnegie Museum. 



Lasmigona cost.vta var. ereganensis, new variety. 



Variety eriganensis is smaller, less elongated and propor- 

 tionately lower than costata. Ventral line straight. Epider- 

 mis in costata light horn-color to dark chestnut in old speci- 

 mens, surface usually with uneven growth lines. In erigO'- 

 nensis always smooth or polished, greenish olive to reddish 

 brown to chocolate-brown, even growth lines. Nacre in costata 

 cream-color to lavender or blue. In variety eriganensis, pink- 

 ish, buff or salmon-color. 



Average for 20 shells : 



costata 



Length Height Diameter 



137 mm. 78 mm. 42 mm. 



96 mm. 55 mm. 27 mm. 



55 mm. 31 mm. 14 mm. 



var. eriganensis 

 Length Height Diameter 

 90 mm. 46 mm. 31 mm. 

 72 mm. 40 mm. 23 mm. 

 65 mm. 36 mm. 19 mm. 



Factors secured as previously show that costata is propor- 

 tionately higher than var. eriganensis, 56% against 53 %o, but 



