ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
277 
very erratic. The more active the species, the larger is the number 
of pulsations. The average for bivalves is 22 beats per minute, tho 
minimum 10, the highest 36, excepting SpJiserium stamineum with 57 ; 
the average for Gasteropocls is 98, the lowest 50, the highest 162. In 
hibernation the pulsations are reduced almost to nothing. 
a. Cephalopoda. 
Notes on Nautilus.* — Dr. A. Willey directs attention to the special 
pre-ocular and post-ocular tentacles in Nautilus. The ordinary non- 
ciliated tentacles adhere to surfaces by the suctorial ridges on their 
lower and inner sides, and they also seize food. The ciliated ocular 
tentacles, white in colour with a little brown pigment, are probably 
accessory olfactory organs associated with the rhinophore which lies 
directly below the eye. In Nautilus the food is found by smell rather 
than by sight. 
Dr. Willey has demonstrated the presence of vibratile cilia on the 
sensory epithelium of the outer osphradia and the post-anal papillae, 
which confirms his view that the latter represent a pair of inner os- 
phradia. 
The Florida Sea-Monster.f — Mr. A. E. Terrill described, on the 
■strength of photographs and local reports, part of the mutilated body of 
what seemed to be an octopus of gigantic size. Examination of the 
tissues shows that they belong to a whale, probably a sperm whale ! 
y. Gastropoda. 
Structure and Affinities of Pleurotomaria.f — MM. E. L. Bouvier 
-and H. Fischer discuss some structural features of these interesting 
forms. As old as the oldest Trilobites, they have persisted until to-day, 
though living specimens have only been found twice. The species 
■described (PZ. quoyana ) belonged to the Blake collection. In some 
respects it is normal enough, resembling Haliotid® or Trochid® in the 
position of its sense-organs, as to its buccal mass, its musculature, its 
cerebral ganglia, &c. It is distinguished (1) by the feeble development 
of the epipodium ; (2) by the peculiar development of the branches of the 
visceral commissure which arise from the cerebro-pallial connectives 
about the middle of their course ; and (3) by the structure of the scalari- 
form nerve-cords in the foot. There is a superior pallial portion, which 
agrees with the pallial cords of the Placophora, and an inferior, the pedal 
portion, which resembles the pedal cords of the same. Thus the pallio- 
pedal cords of Pleurotomaria may be regarded as the result of the 
concrescence of the pedal cords with the ganglionic portion of the pallial 
cords ; and the type illustrates the first stage of a ganglionic concentra- 
tion which becomes more and more accentuated as we ascend the 
Gasteropod series. 
Multiple Reno-Pericardial Canals in Elysia viridis.§ — Dr. E. Hecht 
recognises the correctness of Pelseneer’s observation that there are 
several reno-pericardial canals — a unique character — in Elysia viridis. 
* Quart. Journ. Micr. Sci., xl. (1897) pp. 197-201 (1 pi.). 
t Amer. ^Nat., xxxi. (1897) pp. 304-7 (2 pis.). 
X Comptes Rendus, cxxiv. (1897) pp. 695-7. 
§ Bull. Soc. Zool. France, xxii. (1897) pp. 66-7. 
1897 
tJ 
