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FRESH-WATER BIOLOGY 



15 (16) Pharynx yellowish-brown. Intestine except gland cells bright yellow. 



Stenostomum tenuicauda von Graff 1911. 



B 



Length In chains of 4 zooids 1.5 mm. Slender. Posterior end tapering 

 to a slender tail ($ to ^ of entire length). Point of tail set with adhesive 

 cells. Integument colorless and contains masses of small rhabdites measuring 

 up to 4JM. in length. Excretory pore nearer to intestine than end of body. 

 Two patelliform organs 12 n across and composed of loosely joined spherical 

 bodies. Rochester and Cold Spring Harbor, Long Island, N. Y. 



FIG. 594. Stenoslomum tenuicauda. An undivided chain of four zooids: rh, rhabdites; 

 ig, intestinal glands; ep, excretory pore; ph I, II, pharynx. X 40. (After von Graff.) 



16 (15) Intestine yellowish-green between the round glistening oil drops. 



Stenostomum agile (Silliman) 1885. 



Length of single individual 0.75 mm. Chainsof two zooids measure 1.5 mm., 

 those of five, 4 mm. Light-refracting organs lens-shaped. Rhabdites small. 

 Posterior end bears adhesive cells. Pharynx long and provided with glands 

 throughout its entire length. Sexual organs similar to 5. leucops. Monroe 

 Co., N. Y. 



FIG. 595. Stenostomum agile. (A) Anterior end extended; wgr, ciliated pit; lo, lens- 

 shaped organ; esch, protonephridium; ph, pharynx; da, intestine; g, brain. X 65. (B) 

 Lens-shaped organ. X 125. (After von Graff.) 



17 (10) Integument bright yellow. 



Stenostomum grande (Child) 1902. 



Length of chains of 4 to 6 zooids 2 to 2.2 mm. Pre-oral region, especially 

 the rounded beak-like portion, white. Integument bright yellow, pharynx 

 somewhat darker yellow, intestine deep orange-yellow. Rhabdites small, 

 especially numerous in anterior end. 



Two patelliform organs composed of about 25 spherical bodies. Posterior 

 portion of nearly cylindrical muscular pharynx sometimes shows folds as a 

 result of contraction. Intestine slightly lobed. Rochester, N. Y. Brackish 

 water, Falmouth, Mass. 



FIG. 596. Stenostomum grande. (A) Anterior end: wgr, ciliated pit; so, patelliform 

 organ; ph. pharynx; da, intestine. (B) posterior end: ed, excretory pore. X 55. (After 

 von Graff.) 



