610 The American Naturalist. [July, 
trated in the light-producing apparatus, causing there a sensation, and 
the organ functions by reflex action. The surrounding medium is then 
illuminated by rays perceptible by the eye of the animal. In a word, 
these organs are the organs of a caloric sense. Heat sensations are the 
only kind that can be felt in those abysses when the darkness is relieved 
by occasional gleams of phosphorescent light. I add, finally, that I 
have found in another cephalopod an extremely curious organ con- 
structed in such a manner that it does not perceive light rays, but can 
only receive heat rays, which confirms the hypothesis just advanced,” 
(Bull. Soe. Sci. et Med. de l'Ouest France, t. IT, no. 1893.) 
Verrill’s Organ.—In the funnel of certain Cephalopods, several 
authors have noticed a peculiar cushion-like organ, situated a little 
behind the valve, and this has, for very insufficient reasons, been called 
Verrill’s Organ by Hoyle and others. Its function and homology have 
been the subject of some discussion. Ferussac and D'Orbigny confused 
it with a transverse muscle; H. Müller, in 1852, thought.it was a 
stinging organ; Verrill, in 1882, considered it “ the true homologue of 
the foot of gasteropods;” Laurie, in 1888, from rather insufficient 
material, showed its glandular nature, and believed that it secreted 
mucus, but his observations were criticised by Brock ; Hoyle, in 1889, 
believed that it served to close the funnel. That it is really a mucous 
gland is now proved by the careful observations of G. Jatta (Boll. Soc. 
Nat. in Napoli, vol. VII, p. 45, 1893), who has observed it in 32 
species belonging to 21 genera, thus bringing the number of genera in 
which it has been found from 10 to 27. He describes and figures six 
main modifieations of its arrangement, and gives excellent drawings 
to show its microscopic structure in different stages of its development. 
He concludes that this funnel organ is a mucous gland homologous 
with the pedal glands of other mollusca. If this be so, the organ must 
be somewhat archaic, and one would expect to find it in Nautilus, 
where, to the best of our knowledge it has never been described. (Nat. 
Sci., Feb., 1894.) P 
Preliminary Descriptions of Some New South American 
Characinide.—1l. Tetragonopterus heterorhabdus. This species is 
related to T. schmarde Steindachner. It is readily distinguished from 
T. schmarde by the conspicuous dark lateral band which has on the 
anterior end an oval expansion resembling the humeral spot present in 
in many species of Tetragonopterus. ` 
