198 



HYDRACTINID^. 



Family HYDRACTINID^ Agass. 



HydractinidcB Agass. Cont. Nat. Hist. U. S., IV. p. 339. 18G2. 



HYDRACTINIA Van Bexeden. 



Ilijclractinia Van Bexedkn ; in Bull. Acad. Bel., VEH. 1841. 

 Hydractinla Agass. Cont. Nat. Hist. U. S., IV. p. 339. 1862. 

 Synhijdra Quat. ; in Ann. des Scien. Nat., XX. p. 230. 1843. 



Hydra-ctinia polyclina Agass. 



Hydractinia polyclina Agass. Cont. Nat. Hist. U. S., HI. PI. 16 ; IV. pp. 227-239, 339, Figs. 



33-35; PI. 26, Fig. 18. 1862. 

 Hydra squaviata Fab. Fauna Grdnlandica. No. 338. 

 Alcyonium echinaium Gould. Rep. Inv. Mass., p. 351. 



Hydractinia echinala Leidy. Mar. Inv. New Jersey and Rhode Island, p. 3, PI. X. Fig. 35. 1855- 

 Hydractinia echinata Stimps. Mar. Inv. Grand Manan, p. 11. 1853. 

 Hydractinia echinata McCr. Gymn. Charleston Harbor, p. 66. 

 Clara squamata Morch ; in Beskriv. af Gronland, p. 96. 

 Hydractinia polyclina Pack.; in Can. Nat. & Geol. Dec. 1863. 



As such constant reference is made to Hydractinia in the comparison 

 of the free colonies of Nanomia to the fixed Hydroids, figures of male 



Fig. 330. 



o 



ll_ 



(Fig. 329) and female (Fig. 330) colonies of this species are here intro- 

 duced to facilitate the comparison. 



Point Judith (Leidy) ; Atlantic coast of North America (L. Agassiz). 



Cat. No. 55, Grand Manan, 1859, A. E. Verrill. 



Cat. No. 56, Grand Manan, October, 1857, J. E. Mills. 



Cat. No. 57, Chelsea Beach, L. Agassiz. 



Cat. No. 58, Swampscott, Mass., March, 1859, S. Tufts. 



Cat. No. 59, Nantucket Shoals, July, 1849, L. Agassiz. 



Cat. No. 403, Nahant, Mass., July, 18G2, A. Agassiz. 



Museum Diagram, No. 25, after L. Agassiz. 



Fig. 329. Part of male community of Hydractinia. o, a, sterile individuals ; ?), fertile indi- 

 vidual ; d, male Medusa'; o, o, proboscis; t, elongated tentacle of sterile individuals. 



Fig. 3:!il. Part of female community, o, sterile indiviilual ; 6, I'ertile individual, producing 

 female Medusas, d, c,f, y, h, i ; u, peduncle of mouth ; c, individual with globular tentacles. 



