50 LEIDY'S DESCRIPTIONS OF AMERICAN WORMS. 



ungues or rudimental podal spines, (fig, 16, 5.) and in the posterior part of the body 

 of large individuals, these are frequently nearly as much developed as the others, and 

 there then appears to be eight rovs^s of two each, or rather four rows of four each. 



This worm is infested with extraordinary numbers of a large species of LeucopJinjs. 

 In several instances I saw several thousands issue from wounds made through the 

 muscular investment of the body. The species differs in form from any of those 

 which I know of, and may be characterized as follows : 



Leucophrys clavata, Leidy. Figs. 18, 19. — Body colorless, clavate, very 

 obliquely and concavely truncated anteriorly ; posteriorly attenuated, rounded or 

 acute ; granulo-striated ; with usually six to eight large vacuola. 



Length from l-200th in. to the 1-lOOth in.: breadth l-857th to l-545th in. 



When in a state of division, the posterior part does not present the characteristic 

 truncation until separated from the parent or anterior division. 



REFERENCES TO THE FIGURES OF PLATE 11. 



All the objects have been magnified and viewed by transmitted light. 



Fig. 1. Nais gracilis: a. anterior portion, h. middle, c. posterior. 



Fig. 2. A podal spine of Nais rivulosa. 



Fig. 3. Pristina longiseta : a. developing upper lip of the posterior division ; b, side vievi^ of the upper 

 lip. 



Fig. 4. Oral articulation of Strephuris agilis. 



Fig. 5. Anal do. do. 



Fig. 6. Fasciculus of podal spines and alternating sets anterior to the girdle of do. 



Fig. 7. do. posterior to the girdle of do. 



Fig. 8. Aeolosoma venustum. The arrows indicate the course of the currents produced by the vibrillae. 



Fig. 9. Side view of mouth of do. and course of currents. 



Fig. 10. Lower lip closed. 



Fig. 11. Vibrillated cells from upper lip. 



Fig. 12. Three transverse muscular bands exhibiting the relative connection of the red spots. 



Fig. 1.3. Enchytraeus socialis : a. gizzard-like contraction of the ventricular intestine; b. orifice in the 

 girdle. 



Fig. li. A podal spine of E. socialis : a. spine, b. muscles, c. integument. When the anterior muscle 

 contracts, the spine is retracted forwards, with the point projecting backwards ; the posterior muscle 

 produces a reverse action, and when both contract, the spine is protruded. 



Fig. 15. Free, lenticular corpuscles of the general cavity of the body. 



Fig. 16. Podal spines of Lumbriculus limosus : a. perfected pair, b. rudimentary. 



Fig. 17. Leucophrys from Enchytraeus socialis : a, full grown individual, b. in the state of division ; 

 the lower part has allowed the escape of a globule of sarcous matter from the endosmosis of water. 



Fig. 18. Leucophrys clavata. 



Fig. 19. Outlines of do.: a. in the state of division, b. various forms assumed in its movements. 



