COE : NEMERTEANS OF WEST AND NORTHWEST COASTS. 299 



(PL 2, fig. 18) ; situated deep in the tissues of the head, and com- 

 monly lateral to the brown stripes. 



Proboscis provided with ten large nerves. Basis of central st}v 

 let bell-shaped, short, much enlarged and rather abru})tly truncated 

 posteriorly (Text-fig. 60) ; commonly about .065 

 mm. in length, and .045 mm. in diameter near 

 base. Central stylet rather small, about three 

 fourths as long as basis. Each of the two 

 lateral poiiches usually contains two accessory 

 stylets 



Cephalic glands well developed, filling up a 

 considerable portion of the tissues of head in 

 front of brain. A pair of broad diverticula of 

 the intestinal caecum extend forward above and 

 a little in front of dorsal brain lobes. 



Nephridial system remarkable for its short 

 extent, and because the large efferent ducts open 

 on the head immediately beside the dorsal gang- 

 lia. Nephridial tubules lie above anterior por- 

 tions of the lateral nerves and about the brain, yig. oa.— Tctrastemma 

 but do not extend more than a very short dis- quadriiineatum. Out- 



•^ line of central stylet 



tance behind the ganglia. and basis, x 4io. 



Central sense organs of moderately large 

 proportions, situated a sliort distance in front of the brain. 



Habitat. — Fairly common among ascidians and other growths on 

 piles of wharf in San Pedro Harbor, California. Sexually mature 

 in August. Ova large, opaque ; pale greenish in color. In tide 

 pools, among Cladophora, Pacific Grove, California (H. Heath) . 



82. Tetrastemma (Oerstedia) dorsale (Abildgaard) Mcintosh. 



Planaria c/orsf^Zis Abildgaard, Zool. Danic, 4, p. 25, 1806. 



Tetrastemma dorsalis JMcIntosh, British Annelids, Pt. I, Nemer- 

 teans, Ray Soc, p. 172, 1873. 



Oerstedia dorsalis Biirger, Fauna und Flora des Golfes von Neapel, 

 Monogr. 22, p. 592, 1895. 



Tetrastemma ( Oerstedia) dorsale Coe, Harriman Alaska Expedi- 

 tion, 11, p. 169, 1904. 



