74 



a central clear stripe and two lateral dark ones ; corre- 

 sponding dark lines on the dorsum passing through or 

 connecting a series of yellow spots. Eyes six. Ova 

 yellow, enclosed in transparent membranous ovisacs, of 

 which five or six were collected together, but not coher- 

 ing, nor adhering to the ventral surface, but deposited on 

 dead leaves and covered by the body of the leech. Num- 

 ber of ova in each ovisac varying from eight to fifty. 

 Found May 3d, and probably deposited a few days pre- 

 vious. 



Clepsine minima n. sp. Body flesh-colored, translu- 

 cent ; above delicately lined with black or dark green 

 points. Beneath minutely and irregularly dotted with 

 points that, under the microscope, present the usual radi- 

 ated appearance of pigment cells. Length 6 lines, width 

 1^ lines. Eyes two. Eggs in several ovisacs attached 

 to the venter and carried about by the leech ; color pale 

 red. Body of leech contracted so as to enclose the ovi- 

 sacs. 



Of the genus Nephelis but one clearly defined species 

 was observed. This we believe to be the Hirudo lateralis 

 of Say ; of which a marked variety having numerous 

 fawn-colored blotches on the dorsal surface, and also 

 nearly a uniform fawn color beneath, was observed. 



The ova of both genera, but especially of the Clepsine, 

 afford to the embryologist a fine opportunity for studying 

 the segmentation of the yolk, the gradual histogenic trans- 

 formations, and the final development of organs, the sev- 

 eral stages of the process occupying three or four weeks. 



Not only as a process of animal building by the various 

 stages of histogenetic and morphological transformation 

 is the embryology of these animals peculiarly interesting, 

 but it furnishes also an opportunity of studying the com- 

 pleted structure, in consequence of the transparency of 



