57 



EXPLANATION OF PLATE V. 



Fig. 1. a, b, c, d. Larvae of natural size, in different stages. The three first from 

 the New-River water ; the fourth from the intestine. 



Figs. 2 & 3. The same amplified five diameters ; 2 dorsal, 3 ventral aspect. 



Fig. 4. One of the upper series of branchial appendages. 



Fig. 5. Portion of tegument of the back. 



Fig. 6. Head. a a. Two plaited lobes forming the suctorious disk. b. Mouth. 

 c c. Points of the mandibles just exserted from their sheaths. The 

 remaining portion of mandibles seen indistinctly through the semitrans- 

 parent flesh. 



Fig. 7. Mandibular apparatus and upper portion of alimentary canal, a. Mandibles. 

 b. CEsophagus. c. Proventriculus. d d. Salivary tubes. e. Com- 

 mencement of stomach. 



Fig. 8. Two views of the mandibles, a. First portion, sharp pointed at its extre- 

 mity, and showing two trochanters at its base for insertion of adductor and 

 abductor muscles, and bearing a ball adapted to socket in b, the second 

 joint, c. Third portion for origin of muscles. 



Fig. 9. Larva (natural size) opened to show alimentary canal. 



Fig. 10. Ditto, a a. Intestiniform stomach, b. Contracted portion, c. Point where 

 biliary vessels enter. 



