362 



FRESH-WATER BIOLOGY 



shows as a typical rosette-shaped pharynx. This form k 

 unusual in that the rosette-shaped pharynx does not lead 

 into the intestine from its ventral side, but opens into its 

 anterior end so that when compressed its axis becomes 

 directed forward. Intestine yellowish and extending 

 almost to the posterior end, and having the general shape 

 of the body. 



Fig. 642. Typhloplanid from Lake Canandaigua, N. Y. (A) 

 Swimming freely, showing the dorsal pigmentation. X 55- (B) 

 Slightly compressed with pharynx directed forward. X 40. au, 

 eyes; da, intestine; ekv, anterior branches of protonephridium; g, 

 brain; ph, pharynx; stz, rhabdite glands. (After von Graff.) 



Typhloplanid from Irondequoit, N. Y., von Graff 1911. 



Length 0.5 mm. Without pigment and color- 

 less apart from the brownish-red eyes and the 

 oil drops of the intestine. Eyes irregular in shape 

 and almost twice as far from the side of the 

 body as from each other. The mouth lies on the 

 boundary between the first and second thirds of 

 the body. The anterior end shows many tracts 

 of rhabdites. Collected from a reedy swamp. 



Fig. 643. Typhloplanid from Irondequoit, N. Y. (A) 

 The animal slightly compressed. X 80. (B) Male 

 copulatoiy organ. X 320. au, eye; be, bursa copula- 

 trix; Jr, gland cells; £?5, ductus seminaUs; /, fat drops; 

 ge, ovary; go, genital pwre; kd, granular glands; ks, 

 granular secretion; m, muscles; ph, pharynx; st, tracts 

 of rhabdites; te, testes. (After von Graff,) 



Mesostoma patter soni Schmarda 1885. 



Length 3 to 3.5 mm., 0.6 mm. broad through middle. Color in 

 reflected light brownish except anterior to the eyes which appears 

 grayish from the rhabdites. Intestine yellowish. Body fluid with 

 many cells which contain granules. Eyes directly above the brain. 

 Pharynx rosette-shaped, not far from middle of body. 



Fig. 644. Mesostoma patlersoni. st, tracts of rhabdites; ph, pharyiuE; 

 vi, yolk gland; ut, uterus; be, bursa copulatrix; op, ovary; p, arms; i, 

 testes. X 20. (After SilHman.} 



