918 QUARTERLY CHRONICLE. 
on foetal and young moles lead him to confirm the dental 
formula given on other grounds by Professor Owen. It is 
not, however, at all clear that such a view is the right one, 
for Mr. Bate’s observations would serve to prove that the so- 
called canine of the upper jaw is an incisor. 
AMERICA.—Annals of the Lyceum of Natural History of | 
New York. 1866.—We have to notice a paper on “ The 
Young Stages of a few Annelids,” by Mr. Alexander Agassiz, 
the first part of which we mentioned in our last Chronicle, by 
mistake, as appearing originally in the English ‘ Annals of 
Natural History,’ the fact being that that excellent journal 
had merely reprinted the paper. Mr. Agassiz remarks, in the 
first place, upon the importance of knowing how and where 
to look for the embryonic forms of various marine animals. 
They must not be sought by the side of their parents, but 
along the shore in the scum thrown up by the waves, or 
amongst the gleanings gathered by a fine gauze hand-net in 
surface-dredging. Young Annelids, Echinoderms, &c., thus 
obtained may be kept and watched through their development. 
The first form described is a Planaria (perhaps Pl. angulata, 
Miller). By his observations on this species Mr. Agassiz 
has given most important service to the systematist. It appears 
that the young Planarié exhibit a body distinctly articulated, 
and of a rounded somewhat cylindrical form which they gra- 
dually lose by a retrograde sort of development (as in many 
Crustacea and Arachnida), and become the flat, undivided - 
animals which are so often compared to the naked Gastero- 
pods. 
In Nareda, a Nemertean genus, a somewhat similar and 
remarkable development is described, Loven’s annelid-larva 
being identified with this form. These two cases of develop- 
ment of Turbellarians are of peculiar interest in that they 
differ from those described by Miller, Busch, Gegenbaur, 
Leuckart, and Pagenstecher—in not being instances of 
metamorphosis, but of regular, continuous development. Mr. 
Agassiz remarks that in Echnioderms, as in Turbellarians, we 
find closely allied genera undergoing a widely different de- 
velopment, and that an additional resemblance between the 
two groups is thereby furnished. 
Spirobis spirillum is the next marine worm, the develop- 
ment of which Mr. Agassiz notes. He finds this species in 
America, as here, abundantly attached to Fucus, and has some 
important remarks to make upon the development of the 
tentacles. He observes that the nomadic life of this species 
is not more than eight or ten hours, and that after fixing 
itself in a small tube, development of the anterior part of the 
