272 ANNUAL OF SCIENTIFIC DISCOVERY. 



Every one must have noticed that a footstep -will instantly startle any 

 of the finny tribe that may be lurking under the grassy margin. On 

 the other hand, if the observer be standing still, he may talk or whistle 

 almost as loud as he likes, without the fishes' taking the slightest notice, 

 provided he keeps himself and his shadow out of sight. W. W. Stod- 

 dard On (he Auditory Organs of the Lower Animals. London Intel- 

 lectual Observer. 



How Whales Hear. Had aquatic animals the ears of aerial ones, 

 they would, owing to the superior conduction of sound by water than 

 by air, be stunned by what we should call a slight noise. The whale, 

 then, being a true warm-blood mammal, and at the same time living 

 the life of a fish, how can it hear? The truth, is, that the cetacean 

 ear is a very wonderful combination of the ichthyic and mammalian 

 organ. It hears, as it were, backwards ; for the Eustachian tube opens 

 into the blowhole, while the external orifice is nearly closed. The 

 petrotympanic bone acts as a true otolith, while the mammalian ossicula 

 and tympanic membrane are also present. When, therefore, the ceta- 

 cean conies to the surface for air, it hears aerial vibrations through the 

 Eustachian tube, while at the same time the otolithic ear is immersed, 

 and cognizant of aquatic sounds. Ibid. 



THE EYE OF THE SPERM WHALE. 



At a recent meeting of the Boston Society of Natural History, Dr. 

 Jeffries Wyman gave the following account of a dissection of an eye 

 of the sperm whale and the parts surrounding it : 



On examining the region of the eye, an enormous development of 

 the muscles was immediately observed. The sclerotic coat of the eye 

 was very thick, and likewise formed a very thick sheath around the op- 

 tic nerve, imbedding the bloodvessels, and almost as hard as bone. It 

 was found, however, to contain no ossific matter, and to be simply very 

 dense, fibrous tissue. Behind the globe of the eye, and occupying a 

 large space, was a large venous plexus. The eyelids were thick, and 

 the conjunctiva folded back in such a manner as to permit the eye to 

 recede in the socket. The globe of the eye, together with the optic 

 nerve, weighed three and a half ounces. The powerful retractor 

 muscle, analogous to that of ruminants, weighed five and a half ounces. 

 The other muscles seemed only indirectly connected with the globe, 

 and their use seemed rather to be to open the lid than to move the 

 globe. The muscles which were attached to the lids were of great 

 size, and together weighed one and a half pounds. The object of such 

 muscular power he could not divine. The vascular plexus distended 

 would tend somewhat to force forward the eye, and a sphincter muscle 

 behind the eye would have a similar effect ; but these do not seem to 



*/ 



demand such extensive muscular power. 



ANIMAL EPIDEMICS. 



Don Ramon Paez, in his recent work " Life in the Llanos, Venezu- 

 ela" South America, states, that at certain seasons, nature appears to 

 interfere most actively for the prevention of a superabundance of ani- 

 mal life on the banks and in the waters of the great rivers, which flow 

 through the dense forests and over the Llanos, or luxuriant plains of 

 Venezuela; a circumstance which has a bearing on the extinction 



