MEXICAN AMPHIBIANS—TAYLOR AND SMITH 531 
formation. The maxillary teeth are increased by additions to the 
posterior end of the series. 
The transforming specimens have a dark gray to blackish venter, 
with irregular, ventrolateral cream lines, which may be broken up 
into cream spots. The body may be gray, grayish black, or blackish, 
with few or many cream spots on the sides and tail. 
A reexamination of one rather desiccated paratype (H.H.T.—H.M.S. 
No. 16442) discloses the presence on one side of five phalanges in the 
fourth toe, and four in the third finger, instead of the normal number 
of four and three, respectively; the phalangeal formulae of the hands 
are 2-2-4-2, 2-2-3-2, and of the toes 2—2-3-5-3, 2-2-3-4-3. We 
regard this as an anomaly; however, larger series of fully adult 
specimens may show that we have confused two species. 
AMBYSTOMA VELASCI Dugés 
PuLatTE 18, FIGuREs 3, 4 
Siredon tigrina VELAsco, La Naturaleza, vol. 4, 1879, p. 216 (Laguna Santa Isabel, 
Guadalupe Hidalgo, Distrito Federal). 
Ambystoma velasct Ducks, La Naturaleza, ser. 2, vol. 1, 1888, p. 142 (type locality 
that of Siredon tigrina Velasco). 
Ambystoma tigrinum velascoti WoLTERSTORFF, Abh. Ber. Mus. Magdeburg, vol. 6, 
No. 2, 1930, p. 182, fig. 3, pl. 2, figs. 2-3, pl. 3, fig. 3 (part). 
It is with considerable hesitancy that we are referring to Ambystoma 
velasci two series of specimens, the first constituting a series of 121 
larvae, with a few transforming young, from La Virgin, Puebla (about 
Kilometer 224, 28 km. north of Tehuacan), and the second consisting 
of 189 specimens of larvae and transforming young from the region 
about Lake Texcoco in the Valle de México. Of the entire series, the 
following specimens have been cataloged: Puppia: U.S.N.M. Nos. 
116692-116701, La Virgin, August 21, 1939 (all larvae), and March 24, 
1940 (numerous transforming). M*axico: U.S.N.M. Nos. 116654— 
116667, Santa Magdalena, near Lake Texcoco, in roadside pools, 
August 23, 1939; U.S.N.M. Nos. 116608-116690, San Diego, March 2 
and August 23, 1939. Distrito FrepEraL: U.S.N.M. No. 116691, 
Atzacualeo, October 6, 1939. 
We do not follow Wolterstorff (loc. cit.) in regarding this species as 
having a subspecific relationship with Ambystoma tigrinum. We 
believe that in the assemblage of specimens referred by Dunn (1940, 
p. 157) to this form other species are probably involved. 
From the pond at San Diego two giant specimens presumably 
of this species were taken (E.H.T.-H.M.S. Nos. 22210-22211). 
These apparently are sexually mature. The size of the largest is 144 
mm. from snout to vent; tail, 108mm. No other neotenic specimens 
were encountered. No adequate series of fully transformed specimens 
are available for studies in variation. The Puebla larvae are lighter, 
with less marking than those from the Valley of México. 
