140 



CCELENTERATA 



8 mesenteries (protocnemes), 2 additional pairs of rudimentary protoc- 

 nemes and a few small metacnemes being also present; outer surface 

 ciiaraeterized by 8 longitudinal ridges and often inerusted with sand 

 and other foreign substances: 4 genera and about 20 species. 



1. Edwardsia Quatrefages. Form slender, prismatic; tentacles 16 

 or less in 2 circles of 8 each, of which the outer circle is the larger; 

 2 siphonoglyphs : several species. 



E. elegans Verrill. Number of tentacles 16; length 25 mm.: north 

 of Cape Cod, in shallow water. 



E. leidyi Ver. Number of tentacles 16; length 

 30 mm.; diameter 1.5 mm.; parasitic in Mnemiopsis 

 leidyi: Vineyard Sound and southwards; common. 



2. Edwardsiella Andres. Form cylindrical; 

 tentacles more than 16, usually at least 24, of which 

 8 are in the outer row: several species. 



E. lineata Verrill. Number of tentacles 18 to 30; 

 length 25 to 35 mm.; diameter 3 mm.; color brown: 

 from Vineyard Sound southwards, in 4 to 12 fathoms; 

 common among worm tubes, rocks, etc. 



E. sipunculoides Stimpson (Fig. 225). Tentacles 

 20 to 36; length 12 cm. extended; diameter 4 mm.; 

 color brown: Cape Cod and northwards, in shallow 

 water. 



Fig. 225 



Edwardsiella 



sipunculoides 



(Torrey). 



Division 2. CERIANTHEAE. 



Solitary sea anemones, long and slender, usually imbedded in sand 

 or mud, with numerous tentacles in 2 rows, an outer, marginal, and an 

 inner, circumoral row, and with numerous mesenteries; retractor and 

 sphincter muscles weak or wanting in the adult, ectodermal muscles 

 acting as retractors; but 1 siphonoglyph present; ectoderm with nu- 

 merous gland and nettle cells which discharge sufficient mucus and 

 nematocysts to form a long tube in which the animal lives: several 

 genera with about 20 species. 



Cerianthtjs Delle Chiaje. Lower end rounded and provided with 

 a terminal pore: 2 species on the Atlantic and 3 on the Pacific 

 coast. 



C. americanus* Verrill. Marginal tentacles up to 125 or more; 

 length of body up to 60 cm. extended; diameter 25 mm.; color brown: 

 Cape Cod to Florida, in shallow water. 



* See "The Structure of Cerianthus americanus," by J. P. McMurrich, Jour. 

 Morph., Vol. 4, p. 131, 1S90. 



