CLASSIFICATIONS OF ZOOPHYTES. 457 



the exterior, while in the latter ** the ova are produced in the 

 interior of the body, and are either conveyed outwards by 

 means of oviducts which open by separate orifices, or they 

 are discharged by the mouth." The distinction here first 

 pointed out is a very important one, but in common with all 

 single characters is of itself insufficient, and if rigorously ad- 

 hered to leads to artificial and unnatural combinations. The 

 EXOARIA for example has all its members well and distinctly 

 affined, embracing only three families, 1. the Hydra; 2. 

 Corynea, consisting of the genera Sertularia, Tubularia and 

 Coryne ; and 3. Mittepora, limiting probably this denomina- 

 tion to M. truncata. The ENDOABIA embraces a wider range 

 the Alcyonea equivalent to the Polypes tubiferes of La- 

 marck ; the Tubipora ; the Corallia including the genera 

 Corallium, Gorgonia, Isis, and Antipathes ; the Pennatula ; 

 Zoanthes ; and Madrepores with the subdivisions which have 

 been introduced by Lamarck.* So far the order labours under 

 little error, or is perhaps unexceptionable, but its definition 

 would entitle us to place in it also the Escharidee, the Celle- 

 pores, and Lymnopolypi, which are all very alien to the fami- 

 lies which Rapp seems to have had too exclusively under his 

 view. 



The only other classification I shall notice is Blainville^s 

 the most elaborate of any ; and this author, as it appears to 

 me, is the first who allowed the anatomy of the Polypes, 

 abstractedly considered, to have its due influence on our sys- 

 tems. Notwithstanding, however, Blainville's unquestionable 

 merits, his very defective acquaintance with species will ever 

 prevent him becoming a first-rate systematist : he may sketch 

 the outline, the details he cannot supply, and his attempt 

 has exposed him to numerous errors : he is too fond of gene- 

 ralizations where his facts are few and specifical ; he wants 

 the necessary neatness and brevity of definition, and he 

 evinces everywhere such a total disregard to the old nomen- 

 clature that his system is not likely to become popular, or to 

 be generally adopted. Many of his alterations are excellent, 

 and must meet the approval of all, for surely no one will 



See Edin. Journ. of Geogr. and Nat. Science, ii. p. 406, and Blainv. Man. 

 d'Actinol. p. 59. 



