278 Biliographical Xoticts. 



troduction of seventy-eight pages. We must confess to great dis- 

 appointment -svith this portion of the work. "We had hoped to find 

 here a careful analysis of all that is now known of the reproduction, 

 (development, and affinities of these animals, given in such a way as 

 to arouse at once the incipient naturalist's interest and stimulate 

 him not so much to the collection of specimens as to the observation 

 of facts and the history of species. Instead of this, we find only a 

 short account of the physiology, general morphology, and reproduc- 

 tion, condensed into the briefest possible space — so much so as to 

 be nearlv unintelligible to those not previously acquainted with the 

 subject, and repellent from its laconic brevity. This is much to be 

 regretted. An attempt to describe the reproduction of the Hydroida 

 in such a work as this in the short space of twenty pages is an at- 

 tempt at an impossibility. 



When we pass, however, from the introduction to the descriptive 

 portion of the work, we find everything to merit praise. It is in 

 this that the value of the book consists. It has for some time 

 been hopeless for any beginner to attempt the study of the smaller 

 Hydroida ; the work of Johnston was so greatly behind the day, 

 and the number of species since described by Alder, Allman. Hincks, 

 Strethill Wright, Xorman, Hodge, &c. so great, that, scattered as 

 they were throughout aU sorts of publications, some illustrated and 

 some not, it would have been a hopeless task for any naturalist who 

 had not gradually kept pace with the subject to commence de novo 

 its study. It is therefore with no little interest we take up these 

 volumes, in which all the species that have been described are brought 

 together, carefully defined, and fuUy illustrated. 



Mr. Hincks distributes the Hydroida into three suborders, which 

 he names Athecata, Thecaphora, and Gymnochroa — names which 

 correspond with, but are certainly preferable to, the Tubularina, 

 Sertularina, and Hydrina of Ehrenberg as adopted by Johnston, and 

 with the orders Hydridae, Corynidae, and Sertularidse of Greene, the 

 last being objectionable, not only because, as the former, they are 

 derivatives from the names of genera, but doubly so as having the 

 termination -{d<x, which is always considered to be indicative of 

 families, and not of orders. These suborders contain one hundred and 

 seventy-nine species, of which sixty-one only are to be found in the 

 ' History ' of Dr. Johnston. The chief discoveries have been among 

 the Athecata, as will be evident from the following table, and are 

 for the most part very small forms : — 



Hincks. Johnston. 



Athecata 72 14 



Thecaphora 93 43 



Gymnochroa 4 4 



The descriptions of both genera and species are very carefully drawn 

 up, and are fuU without being diffuse. Dichotomous tables are 

 given at p. 51 of the Introduction ; these are always very useful, 

 and will at once enable the student to refer any species which he 

 may find to its place. 



