coe: nemerteans of west and northwest coasts. 297 



Ocelli situated deep in tissues of head, of moderate size, usually 

 occupying the corners of a square (PI. 2, fig. 25). There is no 

 trace of ijigment between the two ocelli of same side. 



Proboscis provided with ten nerves. Central stylet rather 

 slender; basis rather slender, slightly enlarged posteriorly, of very 

 small size, being only about .05-. 07 mm. in length, and .02-.025 

 mm. in width ; each of the two lateral pouches contains two or 

 three accessory stylets. 



Pigment of longitudinal dorsal bands veiy conspicuous in every 



transverse section of body ; it is situated in the inner portion of the 



ongitudinal muscular layer, appearing as an elongated dark mass 



on each side of proboscis sheath. Pigment masses often occupy 



w^hole thickness of this muscular layer. 



Submuscular glands but little developed. 



Intestinal caecum extends forward through about half the length 

 of esophageal region. 



Nephridia situated in the middle portion of the esophageal region. 

 A single pair of efferent ducts, situated near anterior end of intesti- 

 nal caecum, passes immediately above lateral nerves to open just 

 ventral to lateral margins of body. 



Cerebral sense organs remarkably voluminous ; situated immedi- 

 ately in front of brain and extending somewhat beside and beneath 

 ventral ganglia. Canal to exterior of large size, extending w^ell for- 

 ward to open below lateral margin in a shallow oblique furrow near 

 tip of head. 



Habitat. — Common among bryozoans, tunicates, and other 

 grow^ths on piles of w^harves in the harbor of San Diego, Cali- 

 fornia. Sexual products mature in August. Reproductive pouches 

 of both sexes very voluminous, extending forward well anterior to 

 opening of esophagus into intestine. Ova very large. 



81. Tetrastemma, quadrilineatum Coe. 



Harriman Alaska Expedition, 11, p. 166, PI. 14, fig 5; PI. 20, 



figs. 12, 13, 1904. 



PI. 2, fig. 18; Text-fig. 60. 



This species resembles both T. vittatum (Hubrecht ^ ) Burger 



• Notes from Ley den MiLseum, p. 229, 1870, 



