336 



FRESH-WATER BIOLOGY 



IS (i6) Pharynx yellowish-brown. 



Intestine except gland cells bright yellow. 

 Stenostomum tenuicauda von Graff 191 1, 



Length in chaim of 4 zooids 1.5 mm. Slender. Posterior end tapering 

 to a slender tall (J to j\, of entire length). Point of tail set with adhesive 

 cells. Integument colorless and contains masses of small rhabdites measuring 

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

 Two patelliform organs 12 ii acrbss and composed of loosely joined spherical 

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



Fig. 594. Stenostomum tenuicauda. An undivided chain of four zooids: rh, rhabdites; 

 ig, intestinal glands; ept excretory pore; ph 1, 11, 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 nun. Chains of 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. (S^ 

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



•' / » 

 B 



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 patelhform organs composed of about 23 spherical bodies. Posterior 

 portion of nearly cyUndrical muscular pharynx sometimes shows folds as a 

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

 water, Falmouth, Mass. 



Fig. 506. Stenostomum grande. (.4) Anterior end: Mi«r, ciliated pit; so, patelliform 

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

 von Graff.) 



