NEMERTEA 



203 



segmentation distinct; genital pores marginal; genital organs with the 

 same arrangement as in the Tetraphyllidea : in the intestine of selachians; 

 larvae encysted in teleosts; 2 families. 



Family EHYNCHOBOTHRTIDAE. 

 With the characters of the orders: numerous genera, 

 concerning the value and position of many of which much 

 uncertainty prevails. 



1. Rhynchobothrius Rudolphi. Two bothria, one 

 dorsal and one ventral, which tend to converge at their 

 forAvard ends: many species. 



R. bulbifer Linton (Fig. 331). Bothria oval; neck 

 long and slender; length of body up to 40 mm., with 12 or 

 less segments: in spiral valve of Mustelus canis; cysts in 

 mackerel, bluefish, and other teleosts; common. 



2. Tetrarhynchobothrium Diesing. Four bothria 

 present; head stalk cylindrical; many species. 



T. robustuin (Linton). Bothria elongate; length of 



Fig. 881 



body 24 mm.; segments usually broader than long: in Rhynchohoth- 

 stomach and intestine of skate; common. (Linton). 



Class 4. NEMERTEA.* 

 Nemerteans. Soft, very contractile, and often brightly colored flat- 

 worms, most of which are non-parasitic 

 and live in the sea. The body is usually 

 elongate and more or less tape-like or fili- 

 form, varying in length from 5 mm. to 

 30 m. in the different species; it is unseg- 

 mented, but often has an annulated ap- 

 pearance due to the regularly repeated 

 subdivisions of certain of the internal 

 organs. The mouth is in the ventral sur- 

 face near the front end and the anus is at 

 the hinder end of the body. Dorsal to the mouth (Fig. 332) is an opening 

 into a very deep tubular pocket, extending far back into the body, a portion 



* See "Marine Nemerteans of New England and Adjacent Waters," by A. E. 

 Verrill, Trans. Conn, Acad., Vol. 8, p. 382, 1892. "Die Nemertinen," Fauna u. Flora 

 d. Golfes V. Neapel, by O. Biirger, 1895. '•Nemertini," KJ. u. Ordn., Vol. 4, Supp., 

 1897. "On the Connective Tissues and Body Cavities of the Nemerteans, with Notes 

 on Classification," by T. H. Montgomery, Jr., Zool. Jahrb. Anat., Vol. 10, p. 1. "Notes 

 of the Times of Breeding of Some Common New England Nemerteans," by W. R. Coe, 

 Science N. S., Vol. 9, p. 167, 1899. "Nemertini," by O. Burger, Das Tierreich, 1904. 

 "Synopsis of the Nemerteans, Part I," by W. R. Coe, Am. Nat, Vol. 39, p. 425. 

 "Nemerteans of the West and Northwest Coast of North America," by W. R. Coe, 

 Bull. Mus. Comp. Zool., Vol. 47, 1905. 



Fig. 332 — Diagram of nemertean 

 worm — lateral aspect (Biirger). 

 1, proboscis pore; 2, ventral gan- 

 glion ; 8, mouth ; 4, dorsal gangli- 

 on ; 5, dorsal nerve ; 6, intestine ; 

 7, proboscis ; 8, proboscis sheath. 



