52 The American Naturalist. (January, 
ZOOLOGY. 
The Sensory Canal System of Chondrosteans—Collinge has 
studied especially Polydon, Psephurus and Acipenser. He cannot as- 
sent to naming every branch a canal but prefers to consider sensory 
organs, pits, pores, canals, ete., as parts of one sensory canal system.. 
In this we have to distinguish the canals, the parts of which are 
named, The term cluster pores (=peripheral organs of allis) is given 
to the pores of fine dermal canals running from the main canals or 
-branches; the pinhole pores of many authors are called primitive 
pores from the fact that they occur on the most generalized forms. 
Unbranched canals radiating from certain centres on the head, and with 
an ampulla near the proximal end are called ampullary canals. All of 
the different kinds of sensory organs are grouped under that name. 
The system in Polyodon is described for the first time. It contains 
all the structures except the ampullary canals, which have not been 
found except in Elasmobranchs. The parts are described with some 
detail, as is also their innervation. In the matter of the cranial 
nerves many corrections and additions are made to Van Wijhe’s well- 
known description, especially in regard to the ramus oticus of the tri- 
geminal and the ramus mandibularis of the facial. 
Psephurus agrees pretty well with’ Polyodon but Acipenser is very 
different. The first two show marked 'Elasmobranch features while 
the latter has Teleostean tendencies. Collinge is inclined to support 
the validity of the group Ganoids and to accept its division into Sel- 
achioid and Teleostoid groups, the Acipenserids serving to connect 
the two. While the canal system in its broader features seems to con- 
firm, in this respect, the evidence obtained from other organs, Col- 
linge doubts if it can be employed in any except the most general 
manner. 
The Hypophysis.—Lundborg has studied the hypophysis in tele- 
osts and batrachians and concludes' that it arises as a paired structure 
from the deeper or nervous layer of the ectoderm, its two halves later 
fusing. At first there is an hypophysial stalk, short and solid, which 
later disappears. The future growth is one of folding, ete. The glan- 
dula infundibuli are later in arising from the infundibulum and a ver- 
tical communication always exists between infundibulum and gland. 
1 Zool. Jahrbücher, Abth. Anat. u. Ont., vii, 1894. 
