634 ON ANEURYSMS IN A TIGER. [Junel9, 



{Homarus gammarus Linn.) with symmetrically developed chelse 

 (text-fig. 110, p. 633), recently presented to the ISTatural History 

 Museum by the Directors of Harrod's Stores, Ltd. In the Lobster, 

 as in many other Decapod Crustacea, the large chelse are normally 

 unsymmetrical on the two sides of the body, one being armed with 

 blunt crushing-tubercles and being lai-ger than the other, which 

 has sharp, serrated cutting-edges. Occasionally, however, speci- 

 mens are found, more frequently in the Euroi^ean * than in the 

 American f species, in which both chelae are of similar size and 

 shape. In all such cases hitherto recorded, with the «fexception of 

 one mentioned by Herrick on the authority of a fisherman, but 

 doubted by Stahr, both chelfe were of the seri-ated, cutting type. 

 It has been supposed that this might be due to regeneration 

 after injury, since it is known that, in Brachyura, on removal of 

 the crushing-claw, a cutting-claw is regenerated. Przibram J, 

 however, failed to obtain such " heteromorphic " regeneration in 

 the Lobster, and the present specimen throws still further doubt 

 on the regeneration theory, since it posesses well- developed and 

 quite typical crushing-chelse on both sides of the body. In all 

 other respects it is a perfectly normal male and weighed, when 

 alive, foiir pounds ten ounces. It was caught near Stromness, 

 Orkney, and its peculiar character was noticed by Mr. Thompson, 

 manager of the Fish department in Harrod's Stores, by whom it 

 was brought under Dr Caiman's notice. 



Dr. Caiman also exhibited, on behalf of Dr. A. Duges, C.M.Z.S., 

 a specimen of the Crustacean Palcemon jamaicensis Herbst, from 

 the Atoyac River, Yera Cruz, Mexico. 



Dr. C. G. Seligmann, F.Z.S., the Society's Pathologist, exhibited 

 the aorta of a Tiger showing many aneurysms, and made the 

 following remarks : — 



The specimen shown to-night was derived from a tigress which 

 had been for thii-teen years an inmate of the Society's Gardens. 



The aorta shows advanced arterial disease, most pronounced in 

 the des^cending aorta, where there is marked atheroma and where, 

 in a length of about 180 mm., there are fourteen aneiuysmal 

 swellings varying in size frora that of a pea to that of a fair-sized 

 plum. The two largest swellings, the walls of which are of stony 

 hardness, occur close together on opposite sides of the artery. The 

 tricuspid valves were perhaps thickened, and there may have been 

 some tricuspid incompetence, but there was little or no change in 

 the aortic valves, and, except in the neighbourhood of the 

 anevuysms, there is no appreciable calcification of the vessels. 



The kidneys showed changes of a chronic tubal character, 

 without any marked excess of fibrous tissue. 



* Stahr, Jena. Zeitsclir. xxxii. p. 464 



t Herrick, " The American Lobster," Bull. U.S. Fisli Comm. 1895, p. 143. 



X Przibram, Zool. Aiiz. xxv. p. 12 (1902), and Arch. Entwickmech. xix. p. 191 (1905). 



