Bibliographical Notices. 47 



phytology. II. On the Structure and Physiology of Polypes-, and 

 III. On their Classification. In the last he presents us with a clas- 

 sification of his own. Rejecting sponges altogether, considering 

 them as more nearly allied to vegetables than to animals, he di- 

 vides zoophytes into two sub-classes, first " radiated zoophytes," 

 and second, " molluscan zoophytes ;" the animals of the first sub- 

 class having a symmetrical contractile body, and their mouth and 

 anus in one ; those of the second sub-class having a non- contractile 

 non-symmetrical body, and two openings to the digestive apparatus. 

 Under the first sub-class he places his three orders of Hydroida, 

 Asteroida, and Helianthoida ; under the second that of Asci- 

 dioida. This is a great improvement on the classification of zoo- 

 phytes published by M. Blainville in his ' Manuel d'Actinologie,' 

 but would appear exactly to coincide with the present views of that 

 author, as lately published by M. Holland, a disciple of the great 

 French naturalist in his ' Manuel de Zoologie,' wherein the class of 

 " Polypiares" (corresponding to Dr. Johnston's restriction of the 

 zoophytes) is divided into four sub-classes, " Les Hydriens, les Alcy- 

 oniens, les Actiniens, et les Polypes douteux." This correspond- 

 ence of the present views of M. Blainville with those maintained by 

 Dr. Johnston goes far to support the systematic ideas of the latter. 

 The older arrangements being founded mainly on artificial distinc- 

 tions, such as the presence or absence of a polypidom, must now be 

 entirely laid aside along with systems of conchology in another de- 

 partment of zoology, having served their purpose and now only tend- 

 ing to retard the science they once advanced. 



Dr. Johnston's first order, Hydroida, comprises eleven genera, 

 including fifty species. In the first genus, Hydra, the H. brunnea 

 of Templeton is referred to H. vulgaris, and the Hydra corynaria 

 of the same naturalist (Hydra lutea of Fleming) has its name 

 changed to Hydra littoralis, not being identical either with the Hy- 

 dra lutea or erynaria of Bosc. The Coryne glandulosa of Lamarck is 

 made the type of a new genus, Hermia, thus characterized : — 



" Polype fixed, sheathed in a thin horny membrane, clavate or 

 branched and subphytoidal, the apices of the branches clubbed and 

 furnished with scattered glandular tentacula ; mouth 0." 



A new species of Thoa is dedicated to Mr. Bean of Scarborough. 

 Sertularia pinnata, Templeton, is styled S. hibernir^ . ^ :t i& . . iria 

 ramosa is considered a variety of A. antennina. 



In the second order, Asteroida, five British genera are enume- 

 rated, including seven truly native species and several doubtful. 



