T3907] Zoology. 589 
the tail becomes elevated aboye the head, in the second group the head 
becomes raised above the tail. The utility of these types of organiza- 
tion becomes obvious when the habits of the creatures which exhibit 
them are considered. The first group consists of bottom-haunting fish, 
which are thus enabled to give free play to their tails while scouring 
the sea-bottom in search of food ; the second consists entirely of surface- 
swimming forms which are enabled, by this beautiful adaptation of 
structure, to swim swiftly beneath the surface of the water without the 
risk of their tails emerging, and so cause inconvenience and waste of 
force. The tails of many air breathing aquatic animals, such as the 
sea-snake and the extinct Ichthyosaurus are constructed upon this 
latter principle. (Nature, Feb., 1896.) 
The Spermatheca in some American Newts and Salaman- 
ders.—The term receptaculum seminis has been used to designate cer- 
tain structures in the cloacal wall of the female Necturus maculatus,which 
serve as reservoirs in which the zodsperms of the male are received. 
In order to have a better understanding of the function of these struc- 
tures, Dr. Kingsbury undertook a study of the cloaca in the female of 
six species of Urodeles (American). The chosen species represent fiye 
families, and two orders of Batrachia, and present a good series from a 
purely aquatic to as purely a terrestrial existence. The general result 
has been a recognition of these organs in one form or another in all 
the species under observation, but there is no unity of structure, hence 
the term receptalum seminis is not strictly applicable, and the mono- 
nym spermatheca is proposed instead. In some forms many sperma- 
thecas would be recognized. — 
In Diemyctylus, Amblystoma and Necturus the spermathecas assume 
the form of individual tubules. In Amblystoma the tubules are ar- 
ranged around depressions. In Spelerpes, Plethodon and Desmogna- 
thus consists of a tubular depression of the cloaca into the end of which 
the clustered tubules open. | 
' As to how the spermatozoa find their way into these resting places, 
the author suggests that while the theory of Pfeffer of * positive chemo- 
taxis” is highly probable, yet it is also possible that the entrance of 
the zoisperms may be solely due to their own activity assisted by mus- 
cular contractions of the cloaca and spermatheca. 
The results of Dr. Kingsbury’s observations are thus nig eal 
1. In the genera Necturus, Amblystoma, Diemyetylus, Plethodon 
and Desmognathus, spermathecas are found in the dorsal wall of the 
