86 
PISCES. 
The work, for which the colony is indebted, in the first place, to 
the indefatigable zeal of Dr. Hector, is very well executed. Capt. 
Hutton^s descriptions are clear and precise, and will form a 
sound basis for the prosecution of this study in the different 
parts of the colony. 
River Amazons. Prof. Cope has examined a collection from 
the Ambyiacu River, a tributary of the Amazons, near Pebas, in 
which he distinguishes 76 species, regarding 47 as new. Proc. 
Ac. N. Sc. Philad. 1871, pp. 250-291. 
8. Classipication. 
L. DE Sanctis distinguishes five cerebral types in the class of 
Fishes (Panceri & De Sanctis, ^ Sopra alcuni organi della Cepha- 
loptera,^ Napoli : 1869, 4to). ; ; 
1. Hemispheres ^sed into one compact mass ; olfactory lohes laterally 
coalesced with the hemispheres j optic lobes almost completely covered by 
the cerebellum ; rhomboidal sinus entirely covered by the cerebellum, 
which is lobulato and lamellate. Dicorobatis, Z%j(jccna, Myliohatisy lYi/fjon. 
2. Hemispheres open, and showing partially or completely the third ven- 
tricle j olfactory lobes laterally coalesced with the hemispheres j optic lobes 
and rhomboidal sinus not, or only partly, coyered by the cerebellum ; cere- 
bellum smooth or furrowed. All other SelachiansMud Ganoids. 
3. Hemispheres completely divided into two lateral masses ; olfactory lobes 
transversely divided from the hemispheres ; optic lobes left entirely uncovered 
by the cerebellum j rhomboidal sinus completely covered by the cerebellum, 
which is smooth. Teleostei. 
4. Hemispheres separated by the presence of a special lobe of the third 
ventricle ; olfactory lobes transversely divided from the hemispheres j optic 
lobes quadripartite, uncovered, and showing the Sylvian duct j sinus rhom- 
boidalis completely uncovered j cerebellum rudimental, band-shaped. Cy- 
clostomi. 
5. Branchiostoma. 
No. 247 of the Smithsonian Miscellaneous Collections contains 
an ^"Arrangement of the Families of Fishes, or Classes Pisees,Mar- 
sipobranchii, and Leptocardii,^^ by Theodore Gill, M.D., Ph.D., 
Washington : 1872, 8vo, pp. xlvi & 49. In tl^e introductory part 
the author discusses the points by which he is induced to recog- 
nize three classes instead of one, passing in review the various 
characters which may be used in the division of the class Pisces 
(down to the category of families), and the methods in which 
such characters have been used by authors. The genetic rela- 
tions of the groups are also considered. The second part is a list 
of names of 244 families adopted by the author to serve as a basis 
for the arrangement of the collection of fishes in the Museum of 
the Smithsonian Institution. The following will indicate the 
arrangement adopted by Dr. Gill : — 
