264 Analj/tical Notices of Books. 



than the body. The total length is three inches and three-fourths ; 

 that of the tail being two inches and one-eighth. 



In Ichthyology, a department of natural science which is too 

 generally neglected, there are two articles contained in the pre- 

 sent volume. In one of these, the " Descriptions of two new 

 species of the Linnean genus Blennius^ by C. A. Le Sueur," 

 characters are given of the B. Herminier^ and the B. Hentz. 

 The other, entitled '' Descriptions of four new species of the 

 Linnean genus Blennius^ and a new Exoccetus^ by W. W. Wood," 

 comprising two species of Blennius^ Cuv., the B. geminatus and 

 B.punctatus^ two species oiPholis^ Artedi, the P. novem-lineatus^ 

 and P. quadrifasciatus^ and the Exoccetus appendiculatus ; figures 

 being given of the two last-mentioned species. 



Of the two papers that relate to the MoUusca, one is peculiarly 

 interesting. It is entitled " Remarks .on the floating apparatus, 

 and other peculiarities of the genus Janthina^ by Reynell Coates, 

 M. D.," and illustrates, from the personal observations of the 

 authour during a recent voyage to the East Indies, the correctness 

 of M. Cuvier's statement, that there exists no anatomical con- 

 nection between the animals and the air-cells of their float. Of 

 the mode in which this organ is constructed, or rather repaired, 

 the following description is given. Individuals being placed in a 

 tumbler of brine, and a portion of the float being removed by the 

 scissors, the animal very soon commenced supplying the deficiency; 

 the foot was advanced upon the remaining vesicles, until about 

 two-thirds of the member rose above the surface of the water ; 

 it was then expanded to the uttermost, and thrown back upon the 

 water, like the foot of a Lymneus when commencing to swim ; 

 in the next place it was contracted at the edges, and formed into 

 the shape of a hood, enclosing a globule of air, which was slowly 

 applied to the extremity of the float. A vibratory movement 

 could now be perceived throughout the foot, and when it was 

 again thrown back to renew the process, the globule was found 

 enclosed in its newly constructed envelope. From this it results 

 that the membrane which encloses the cells is secreted by the 

 foot, and that it has no attachment to the animal other than the 

 close cohesion resulting from the nice adaptation of proximate 



