Chap. II. 



THE DIFFERENT RADIATA. 



59 



Fig. 39. 



Fig. 40. 



fuiKlaniental differences which distinguish the 

 Polyps from the Acalephs, and at the same 

 time incline more and more towards iTuiting 

 the Hydroids as well as the Siphonophoraj 

 with the genuine Acalephs. Incidentally, I 

 would also remark that I entertain no doubt 

 respecting the Hydroid affinities of Lucer- 

 naria {Figs. 39 and 40). Moreover, their 

 resemblance to the young Medusce is very 



great {Flys. 41, 42, and 43), especially during the incipient stage of their Strobila 



state of development. 



LUCERNAEIA, 



Seen in profile. 

 a Peduncle. — h b Tentacular 

 bunches. 



LUCERNARIA, 



Seen from above. 

 n Mouth. — c c Ovaries. — 

 h b Tentacular bunches. 



Fig. 41. 



Fig. 43. 



Scyphostoma of 

 AUEEI.IA FLAVIDULA, P^r. & LeS. 

 In this stage of growth, Aurelia is 

 simply a HyJroid. 



Strobila of 



AUEELIA FLAVIDULA, P^r. & LeS. 



a Scyphostoma reproduced at the base 

 of a Strobila 6 6, all the disks of which 

 have dropped off but the last. 



Ephyra of 

 Aurelia flavidula, Pi'r. & LeS- 

 c Mouth. — ff Eyes. —0 Ovaries.— 

 «• w Tentacular spaces. 



The types referred to the class of Polyps are not less diversified than those 

 referred to the class of Acalephs ; nor do the different writers upon that subject 

 agree more closely in the views which they entertain respecting their aflQnities. 

 The type which has always been considered as forming the bulk of the class of 

 Polyps is that of the Corals. The Actiniae have been by turns associated with 

 them, and separated from them. As we have already seen, the Hydroids have 

 also, for a long time, been united with them by all naturalists, until doubts arose 

 respecting the correctness of this combination, in consequence of the discovery of 

 alternfite generations among them. Besides these we find, farther, the Bryozoa 

 united with the Polyps even to this day by many naturalists; though the re- 

 searches of Milne-Edwards and Audouin,^ published more than twenty years ago. 



' Edwards (H. Milne) et Audodin (J. V.), 

 Recherches sur les animaux sans vertebres faites 

 aux iles Chausey, Ann. Sc. Nat. II. p. 20. — 

 Milne-Edwards alone published more extensive ac- 

 counts of those observations: Recherches Anato- 

 miques, Physiologiques, et Zoologiques sur les 

 Polypes; Ann. Sc. Nat. 2de ser. 1838, IV. p. 321; 



1840, VI. p. 5 ; 1841, VIII. p. 321 ; and 1842, 

 IX. p. 193. The opinion that tlie Bryozoa are 

 not Polyps, but a low type of Molhisks, had al- 

 ready been expressed by K. E. v. Baer, in 1827, 

 in his Beitriige zur Kenntniss der niedern Thiere, 

 Nova Acta Academic Naturce Curiosorum, Vol. 

 XIII. 



