166 PROCEEDINGS OF THE ACADEMY OF 



This description is taken from alcoholic specimens. They ex- 

 hibit considerable variation in size, and to some extent in detail. 



Prof. Verrill has described what he views as two species of 

 Artemia distinct from the well-known A. salina. One he names 

 A. gracilis from near New Haven, Conn. ; the other A. Monico from 

 Lake Mono, Cal. That from Salt Lake differs from either of them 

 as much as they do from A. salvia, and with the same propriety 

 ma}^ be regarded as a distinct species. I am disposed to view 

 them all as varieties merelj r of A. salina. 



Measurements of two specimens of the Salt Lake Artemia are 

 as follows : 



Total length 



Length of body .... 



Breadth of body with limbs 

 Breadth of head at eyes . 

 Breadth of thorax where widest 

 Length of first joint of abdomen 

 Breadth " " . . 



Length of sixth " " 

 Breadth " " " . 



Length of caudle setae 

 Length of antennae .... 

 Length of claspers of male 

 Breadth " " 



Breadth of ovarian sac 

 Diameter of eggs .... 



Remarks on Fossil Shark Teeth Prof. Leidy stated that from 

 time to time he had observed specimens of teeth from various 

 cretaceous formations which were identical in character with those 

 of Lamna elegans and L. cuspidata of tertiary deposits except 

 that they were devoid of the lateral denticles. He had now in his 

 possession well-preserved specimens of such teeth, unabraded, but 

 exhibiting no trace of the existence of lateral denticles. There 

 were teeth of the L. elegans variety found with the skeleton of 

 Hadrosaurus Foulkii in New Jersej T , and others from the creta- 

 ceous of Mississippi and Kansas. There were also teeth of the 

 L. cuspidata. variety from the cretaceous of Kansas, and one in a 

 block of chalk from Sussex, England. The absence of the lateral 

 denticles in all the cretaceous specimens he thought could hardly 

 be accidental, and suspected that these teeth represented the oxy- 

 rhina ancestors, of the tertiary Lamna elegans and L. cuspidata, 

 who lived during the cretaceous era. 



