GULF OF MEXICO 



309 



Family TETRASTEMMATIDAE 



Tetrastemma candidum Mcintosh, 1873, Verrill, 1892; 

 Coe, 1940, 1943 



Fasciola Candida Muller, 1774. 



These little worms may be identified by the pale 

 greeji or yellowish green body without markmgs. 

 Young individuals are pale yellow laterally and 

 green medially. There are two pairs of conspic- 

 uous reddish brown ocelli anterior to the brain. 

 The stylet basis is rounded at both ends and 

 slightly enlarged posteriorly. Length of body 

 when mature 10 to 20 mm., occasionally 35 mm.; 

 width 0.5 to 1.5 mm. 



Locally common among Bryozoa, algae, and 

 other growths in the intertidal zone and below 

 from Labrador to northern Florida and on the 

 Gulf coast at least as far west as Louisiana. 

 Found also on European coasts, Madeira, and 

 South Africa, as well as on the Pacific coast from 

 Alaska to Mexico. This is a typical cii'cumpolar 

 species. 



Tetrastemma vermiculus Stimpson, 1857; Verrill, 1892; 

 Coe, 1943 



Polia vermiculus Quatr., 1846. 



This species resembles T. candidum in many 

 respects but differs in having a light yellow or 

 reddish body variously spotted with brown and 

 in having the two ocelli of the same side connected 

 by a band of dark pigment. Some individuals 

 have paired lateral spots at regular intervals along 

 the entire length of the body. 



Locally common among algae and Bryozoa in 

 the intertidal zone and below from the Bay of 

 Fundy to northern Florida and on the Gulf coast 

 westward to Texas. Found also on European 

 coasts from Norway to Madeira. 



Order 4 BDELLONEMERTEA 



Family MALACOBDELLIDAE 

 Malacobdella grossa (O. F. Muller), 1776 



M. grosa Burger, 1895; Gering, 1911; Riepen, 1933; Coe, 

 1940; M. obesa, M. mercenaria Verrill, 1892. 



Body short and broad, wider at posterior end 

 which bears a comparatively large suction disk. 



Length when mature 20 to 40 mm., width 8 to 

 15 mm. Color white, gray, pale yellow, or brown- 

 ish. Ocelli and cerebral sense organs absent. 

 Alimentary canal narrow, cylindrical, and convo- 

 luted ; without diverticula. Proboscis slender with 

 weak musculature and without stylets. Gonads 



in both sexes small and numerous. Eggs that are 

 artificially fertilized develop rapidly without 

 metamorphosis. 



Commensal in the mantle cavity of various 

 species of bivalve moUusks; on the Atlantic and 

 Gulf coasts more commonly in Venus mercenaria 

 than in any other species. Widely distributed on 

 European shores as far south as the Mediterra- 

 nean; on the American Atlantic coast from Nova 

 Scotia to Florida, on the Gulf coast westward to 

 Texas, and on the Pacific coast as far south as 

 California. It probably causes little, if any, injury 

 to the host, since it feeds mainly on the larger 

 particles which the clam draws into its mantle 

 cavity but does not ingest. 



BIBLIOGRAPHY 



BtJRGER, Otto. 



1904. Nemertini. Das Tierreich 20: 1-151. 

 Coe, Wesley R. 



1929-34. Regeneration in nemerteans. Jour. E.xp. 



Zool. 54: 411-459; 57: 109-144; 61: 29-41; 67: 283- 



314. 

 1930. Ase.xual reproduction in nemerteans. Physiol. 



Zool. 3: 297-308. 

 1940. Revision of the nemertean fauna of the Pacific 



coasts of North, Central, and northern South America. 



Allan Hancock Pacific Exped. 2: 247-323. 



1943. Biology of the nemerteans of the Atlantic coast 

 of North America. Trans. Connecticut Acad. Arts 

 and Sci. 35: 129-328. 



1944. A new species of hoplonemertean (Paranemertes 

 biocellata) from the Gulf of Mexico. Jour. Washington 

 Acad. Sci. 34: 407-409. 



1951. Geographical distribution of the nemerteans of 

 the northern coast of the Gulf of Mexico as compared 

 with those of the southern coast of Florida, with 

 descriptions of three new species. Jour. Washington 

 Acad. Sci., 41: 328-331. 



1951a. The nemertean faunas of the Gulf of Mexico and 

 of southern Florida. Bull. Mar. Sci. Gulf and Carib- 

 bean, 1: 149-168. 



GiRARD, C. 



1893. Recherches sur les Planari^s et les N^mertiens 

 de r.'Kmerique du Nord. Ann. Sci. Nat., Zool. 15: 

 145-310. 

 Humes, Arthur Grover. 



1942. The morphology, taxonomy, and bionomics of 

 the nemertean genus Carcinonemertes. Hlinois Biol. 

 Monog. 18: 1-105. 

 Verrill, A. E. 



1892. The marine nemerteans of New England and 



adjacent waters. Trans. Connecticut Acad. Arts 



and Sci. 8: 382-456. 



More complete bibliographic references to the American 



species may be found in the publications by Verrill (1892), 



Burger (1904), and Coe (1940, 1943). 



