1576 The Zoologist— Makch, 1869. 



founded cannot be regarded as a typical larva, as it had already made 

 considerable progress in its melamorpliosis. This appears to be dis- 

 tinctly shown in the colour-markings, which suggested the specific 

 name, and likewise in the dorsal and caudal membranes, which have 

 apparently been materially diminished by absorption. The evidence 

 of partial transformation seems to be equally strong, also, in the case 

 of the specimen from Nebraska, subsequently figured and described 

 by Prof. Baird under the name Siredon melanosticta, which is possibly- 

 only a variety of S. lichenoides.* The coloration, the irregular outline 

 of the membranes, the rounded extremities of the branchial processes, 

 as well as the arrangement of the palatine teeth, all indicate that the 

 animal figured had already entered upon the preliminary stages of 

 metamorphosis. In each of these cases, however, it is not improbable 

 that the alteration may have been temporarily, or possibly even per- 

 manently, suspended before the animal was captured. Aside from 

 the features which may be the result of partial transformation, the 

 siredons from Lake Como do not differ essentially' from Prof Baird's 

 original figures of S. lichenoides, except in having a somewhat 

 broader head, and in not having the dorsal membrane extend to the 

 occiput, diflerences which may be due merely to locality, as the 

 type specimen came from a point about four hundred miles farther 

 Ciouth. 



The siredons obtained at Lake Como, as already stated, were from 

 five to ten inches in length. The colour of the body is a very dark 

 olive above and a light olive below, while the fimbriae of the external 

 branchiae are nearly or quite black. On either side of the body are 

 twelve costal grooves, not including the inguinal. The skin is smooth 

 and transparent, and shows beneath it the ends of innumerable glands, 

 thickly crowded together. In specimens preserved in alcohol these 

 glands project, making the surface appear granular. The dorsal mem- 

 brane commences a short distance from the base of the head, and both 

 this and the lower membrane extend a little beyond the end of the 

 tail, thus making the extremity slightly emarginate. The carpus and 

 tarsus are unossified. The digits are broad at the base, depressed and 

 triangular. The fourth toe is longest, and has four phalanges. The 

 head is broad and flat, and the muzzle rounded. The external nostrils 

 are smaller, and slightly nearer together than the interior nasal 

 openings. The eyes are round, and the iris of a yellowish metallic 



* Pacific Railroad Report, vol. x., plate xliv., fig. 1; and vol. xii., part 2, p. 306. 



