ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
447 
Mesarsenia Lave the third arm of the male hectocotylized, while some 
of the suckers of the other arms are in that sex much larger than those 
of the female, in certain genera ; in others the tips of the arras undergo 
modification ; here come the Octopoda,. The Decapoda are divided into the 
Chondropliora, Sepiophora, and Phragmophora ; the first of these groups 
consists of two suborders— the Ophistharsenia ( = Sepiolidae), in which one 
of the first or dorsal arms is generally hectocotylized, and the Prostharsenia 
(= CranchiidaB, Chiroteuthidse, Ommastrephidae, and Loliginidas), in 
which there is hectocotylization of one of the fourth, i.e. ventral arms. 
In the Sepiophora (= Sepiidae) and the Phragmophora ( = Spirulidae), 
the hectocotylization is on the basal portion of the fourth or ventral arm. 
The synonymy and distribution of twenty species are given. 
Terrestrial Air-breathing Molluscs of United States.* * * § — Mr. W. G. 
Binney has published a third supplement to his fifth volume on these 
Molluscs, in which the eastern province species are given as well as 
other addenda which bring the subject down to the first day of this 
year. Avion foliolatus Gould has been rediscovered, after fifty years’ 
d isappearance. 
<y. Gastropoda. 
Nudibranchs collected by the ‘Blake.’f — Dr. B. Bergh gives an 
account of the seven, all new, Nudibranchs collected by the U.S. steamer 
‘ Blake ’ in the Gulf of Mexico and the Caribbean Sea. Opportunity 
is taken to revise or make additions to the characters of the genera. 
CJiromodoris scabriuscula is remarkable for the hard warts on the back 
and the development of the cutaneous spicules, as well as for its strong 
median tooth-plates. A species which is called anceps is, with some 
doubt, assigned to the genus Phlegmodoris. The anatomy of all the 
species is very carefully detailed. 
The “Opaline Gland” of Aplysiidse.J — To a previous report § of 
Sig. G. F. Mazzarelli’s investigation of the “opaline,” “poison,” or 
“ grape-like ” gland of Aplysiidae, the following facts from the completed 
memoir may now be added : — The gland of Bohadsch, as the author 
prefers to call it, usually receives an arterial trunk directly from the 
aorta, and is always innervated from the right pedal ganglion. It may 
consist of odoriferous, chromatogenous, and giant mucous cells, derived 
from a gradual increase and modification of ectodermic elements which 
sink into the subjacent connective and muscular mesoderm. According 
to the nature of the component cells, the gland may emit a white and 
odoriferous, a violet, or a mucous section, of which the first and third 
are usually combined in all the species, while the second is only known 
in Aplysia limacina and A. punctata. There is, however, great variability 
in the character of the secretion. The products of the gland are regarded 
by Mazzarelli as excretory, while he believes that their odour and their 
power of clouding the water have a defensive value. Morphologically, 
the organ is probably comparable to a glandular sac recently described 
in Oscanius ( Pleurobranclius ) by A. G. Bourne. 
* Bull. Mus. Comp. Zool., xix. (1890) pp. 183-226 (11 pis.). 
t T. c., pp. 155-81 (3 pis.). 
% Mem. Estr. Atti It. Accad. Napoli, iv. (1890) pp. 26 (2 pis.). 
§ This Journal, 1890, p. 164. 
