432 



REVIEWS. 



an outer or ectoderm, and an inner or endoderm, which correspond, 

 in mode of growth, with the primitive layers of the germ. 



No distinct neural and haemal regions. A nervous system absent 

 in most. 



Peculiar urticating organs, or thread cells, usually present. 



I 



Class 1. 



Hydrozoa. 



Coelenterata, in which the wall 

 of the digestive sac is not sepa- 

 rated from that of the somatic 

 cavity, and the reproductive or- 

 gans are external. 



Order 



„ 



1.— Htdeidje } 



2.— Corynid^: > G6 

 3. — Serttjlarid^ ) 



4.— CALYCOPIIORLDiE \ 6? 



5. — Physophoridje } 

 6. — Medusiiwe 68 



7. — LuCERNARLDiE. 69 





Class 2. 



ACTINOZOA. 



Coelenterata, in which the Avail 

 of the digestive sac is separated 

 from that of the somatic cavity 

 by an intervening space, sub- 

 divided into chambers by a series 

 of vertical partitions, on the faces 

 of which the reproductive organs 

 are developed. 



Order 1. — Zoaotharia 70 

 „ 2. — Eugosa 

 „ 3. — Alcyonaria 71 

 „ 4.— Ctenophora. 72 



66 Exoarii, Rapp, 1829; Zoocorallia oligactinia, IBIW&ib&eg, 1834; Dimorphcea, 

 Ehrenberg, 1836 ; Sertulairiens, Audonin et Milne Edwards, 1836 ; Hydroida, 

 Johnston, 1836; Nudibracbiata, Farre, 1837; Polypiaria, Gray, 1842; Hydrozoa, 

 Owen, 1843 ; Hydroidea, Dana, 1846 ; Hydraria, Milne Edwards, 1850 and 57; 

 Hydriformia, Van der Hoeven, 1856 ; Hydras, Bronn, 1859. 



67 Acalephes Hydrostatiques (with PorpHa and Velella), Cuvier, 1830; Siphono- 

 phora, EscliscJwltz, 1829; Physogrades, Diphyes, et Chondrogrades, De Blainville, 

 1834 ; Schwimmpolypen or Hydroidea nechalca (besides Porpita and Velella), 

 Kolliher, 1853. 



68 Cryptocarpee, Eschseholtz, 1829 ; Gymnophthalmata, Forbes, 1848 ; Craspe- 

 dota, Gegenbaur, 1857. f 



69 This oi'deris divided into three families: Luccrnariadse, Pelagidas, and Rhizo- 

 stomidse. The synonyms of Lucernariadse {Johnston) are as follow: — Cylicozoa or 

 Calycozoa, Leuckart, 1848; Podactinaria, Milne Edwards, 1850 and 57. The two 

 other families correspond to Phanerocarpse of Eschseholtz, 1829; Medusidae and 

 Rhizostomidse, Brandt, 1833 ; Rhizostouieae, Lesson, 1843 ; Steganophthalmata, 

 Forbes, 1848 ; Discophora, Kolliher, 1853 ; Acraspeda, Gegenbaur, 1857; Disco- 

 phora, Agassiz, 1860. 



70 Helianthoida (minus Lucernariadse), Johnston, 1836 ; Zoantharia (minus 

 Rugosa), Milne Edwards, 1836; Actinaria, Dana, 1846. 



71 Alcyonaria of Milne Edwards, also of Dana ; Zoophytaires on Ctenoceres, 

 De Blainville, 1834; Octactinia, Ehrenberg, 1834; Asteroida, Johnston, 1836. 



72 Ctenophora of Eschseholtz, 1829 ; Beroes ou Ciliobranches (Ciliograda), De 

 Blainville, 1834. 



