98 PEOCEEDINGS OF THE ACADEMY OF 



those characters are highest which cover the greatest number of cases, ( i. e. of species.) 

 Second, the extent covered bg each of a given number of characters being equal or 

 nearly so, that is highest which expresses modifications of those characters which dis- 

 tinguish the group which embraces them all, from other groups of similar high rank. 

 Third, the loivest grade of characters, except the specific, i. e. those tvhich distinguish 

 nearest allies, are always those ivhich are assumed latest in the life history of each. 



These rules are without significance if they do not point to a derivative 

 hypothesis. 



BATRACHOSEPS Bonap. 



Tongue adherent anteriorly. Digits 4 — 4. A large parietal fontanelle. 

 Premaxillary pierced by a fontanelle, single. 



This genus embraces the forms which may be considered the lowest in the 

 family, if Necturus be excluded. It difters from Hemidactylium nearly as Opheo- 

 batrachus does from Spelerpes, i. e., in the non-ossification of the parietal bones. 

 This low grade of development is here seen in the extremities also, which are 

 much reduced, and the snake-like form of one of the species. The species are 

 three, as follows : 



I. Costal plicai 18; the toes well developed, palmate. 



Outer posterior toe well developed ; hind limb extending over 7-5 costal 

 interspaces, fore limb to orbit; tail equal body and head to orbit, more slender 

 than the body; belly yellowish B. pacificus. 



II. Costal plicae 20 — 1 ; toes very rudimental, little distinct. 



Hind limb extending over six costal interspaces ; fore limb nearly to orbit ; 

 tail as long as body and head to orbit ; width of head seven times from muzzle 



to groin ; belly black ' B. nigriventris. 



Hind limb extending over four costal interspaces ; fore limb not to angle of 

 mouth ; tail thick as body, as long as body and head plus the length from 

 muzzle to axilla; width of head eight times from muzzle to groin ; belly brown. 



B. attenuatus. 

 Batrachoseps nigriventris Cope. 



This small species resembles the first in general proportions, but is nearer 

 the next in the rudimental condition of the limbs. 



Muzzle shorter than oi'bit ; upper lip slightly angulated. A groove from the 

 orbit posteriorly ; a gular fold. Costal grooves extending to vertebral line, 

 but not curved forwards there as in H. scutatum; extending across abdo- 

 men. Body slightly compressed. The tail as stout as the body at the base, 

 subquadrate in section, becoming compi-essed at the tip, strongly annulate, 

 not swollen. Inner digits on both feet minute. Vomerine series well devel- 

 oped ; sphenoidals as in the others. 



Lines. 



Total length 22 



Do., exclusive of tail from vent 13-5 



Muzzle to axilla 3-5 



Width head 1-7 



Length fore limb , l-S 



" hind " 2 



Color above deep brown, separated abruptly from the black of the lower 

 surfaces ; tail black. 



Two specimens of this species were brought to the Museum of Academy 

 Natural Sciences from Ft. Tejon, California. One of these, Mus. Smithsonian, 

 is No. 6734, 1 specimen, Ft. Tejon, Cal. 1865, Acad. Nat. Sciences. Geo. H. 

 Horn, M. D. 

 Batrachoseps attenuatus Eschscholtz. 



Salamandra attenuata Esch., Zoological AtJas, pt. v, pi. 21, figs 1 — 14. 

 Batrachoseps attenuata Bonap., Fauna Italica, ii, 1841. Baird, Journ. Ac. Nat. 

 Sci. Phil, i, 288. Gray, Cat. Brit. Mus. p. 41. Hallowell, J. A. Nat. Sci. Phil. 

 1858, 348. 



[May, 



