Chap. V. ' EUDENDRIUM DISPAR. 285 



belonging to the genus Eudendrium of Ehrenberg. In the first place, we may 

 distinguish, under the name of Eudendrium, the type of these Hydroids, the pro- 

 boscis of which is large and prominent, and the medusa3-buds permanently sessile ; 

 next the type with short proboscis, from Avhich arise the free medusa3 known as 

 Bougainvillia and Lizzia, and, finally, a third type, embracing the free medusfB which 

 I have described under the name of Nemopsis, the Hydroid of which McCrady 

 has first ascertained to be a free locomotive form, allied to Acaulis of Stimpson. 

 These three types constitute, I believe, three distinct families. For more details 

 upon the Nemopsidaj I refer to the paper of McCrady upon the Hydroids of 

 South Carolina. Representatives of the two other families are described in the 

 following sections. 



SECTION II. 



EUDENDRIUM DISPAR AG. 



For many years I have known twb Hydroids, from the shores of Massachusetts, 

 which I have for a long time considered as two distinct species, and described 

 as such under Nos. I. and II., though they are now figured (PI. XXVII. Figs. 10- 

 21 and 22-26) as one and the same species, it having of late been ascertained 

 that they are, respectively, the male and the female stock of the same kind of 

 Hydroids. 



No. I. Proles liydroidca. — This hydroid is a true deei>water animal, never being 

 found on the shore, properly speaking. It may, however, he obtained in covered, 

 rocky pools, on the ledges which lie far out in the ocean. It has a similar mode 

 of branching, and is very nearly of the same size and color as the hydra of 



"> DysmorpJwsa, Krolin, Wiegm. Archiv, XVII Jahrg., ? Eudendrium (con/ertum), Alder, Cat. Zociph., 1857, 



Bd. 1, 1851, p. 203. p. 13, PI. I. Fiffs. 5-8. 



Laomedea {tenuis). The medusa, Allman, An. Mag. " " Wright, An. Mag. Nat. Hist., 



Nat. Hist., 1859, IV. p. 3G7. 1861, VIII. p. 126. 



Corywe (acMfcata), Wagner, Oken's Isis, 18.33, p. 256, 1 Dicoryne, AWman, An. Mag. Nat. Hist., 2d ser., 

 n. XI. Figs. 1-9. 1859, Vol. IV. p. 369. 



" (r!(/(/nm), Wagner, Icones Zoot., 1841, PI. " Allman, An. Mag. Nat. Hist., 2d ser.. 1861. 



XXXIV. Figs. 16 and 17. Vol. VIII. p. 168. 



^Eudendrium {confertum). Alder, Annals and Maga- ? Cionistes, Wright, An. Mag. Nat. Hist., 2d ser., 1861, 



zinc Nat. Hist., 2d ser., Vol. VIII. p. 123. 



1856, Vol. XVIII. p. 354, 1 Hydractinia, Alder, Edinb. New Phil. Jour., 1862, 

 PL XII. Figs. 5-8. p. 144. 



