338 



FRESH-WATER BIOLOGY 



23 (22) Without eyes Microstomum caiidatum Leidy. 



cp-m-i 



-ph 



Length 1.5 to 3 mm. Commonly in chains of 2 to 8 zooids. 

 Nematocysts in place of rhabdites. Color of integument white, in- 

 testine yellow. Ciliated pits directly dorsal to mouth. Pre-oral 

 portion of intestine short. Anterior end bluntly rounded. Poste- 

 rior end narrower, bluntly pointed, tail-like, elevated. In standing 

 water and small brooks, Monroe Co., N. Y.; near Philadelphia, and 

 in West Twin Lake, Charlevoix, Mich. 



Fig. 5<jg. Microstomum caudatum. b, brain; ph, pharynx; cp, ciliated 

 pit. (After SUliman.) 



24 (21) 



25 (26) 



Pharynx opens into anterior end of the intestine, which has short 



lateral diverticula Subfamily Macrostominae. 



Only one genus Macrostomum . . 25 



Chitinous portion of copulatory organ a broad straight funnel with 

 the slender point bent at a right angle or nearly so and 

 bearing on its convex side the small opening. Vesicula 

 seminaUs and vesicula granulorum connected by a narrow 

 tube. . Macrostomum appendiculatum (O. Fabricius) 1826. 



..^■f" \ 



This is the form known as M. kysirix Oersted 

 1843. Length 2 mm. Unpigmented, transparent. 

 Body flattened especially at the ends. The spatulate 

 posterior end set with adhesive papillae. Rhabdoids 

 and long sensory hairs conspicuous. Two eyes, 

 black. Protonephridial tubes open on median dorsal 

 side back of the sUt-like mouth. Testes and ovary 

 both paired. Asexual reproduction not known. In 

 running and standing water. Monroe Co., N. Y.; Lin- 

 coln, Neb. 



Fig. 600. Macrostomum appendiculatum. (A) Entire 

 worm: b, brain; e, eye; ph, pharynx; di, diverticulum of 

 intestine; *, intestine; te, testes; vd, vas deferens; vg, 

 ductus seminaUs; vs, seminal vesicle; vg, vesicula granu- 

 lorum; ch, chitinous spicule of cirrus; ^ and $ , male 

 and female genital pores; ow, ovary. X35. (After von Graff.) 

 (B) Chitinous spicule eolaiged. X 350, (After Luther.) 



