320 U. Ss. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
is mixed black and dull brownish yellow or whitish, which tint shows almost uniformly beneath 
and broadly on the margin and tip of the tail. "When the tail is flattened at the tip it shows 
distinctly a very broad bar of black within the light margin, and another narrow bar of the 
same half way between this and the extreme base, which is also black. There are thus exterior 
to the dark base two bars of black and three of whitish, the basal half of the hairs being light 
colored, with a narrow dark bar in the centre, as also at the base; the terminal half black and 
light colored, about equally divided, except towards the tip where the black is more extended. 
Specimens vary, as ulready stated, in the tint of the ground color above and in other charac- 
ters, the length of hair on body and tail, &c. Sometimes the dusky base to the caudal hairs is 
obsolete. In one (231) the hairs at the tip are very long, over two inches; but this seems 
abnormal. Many of these differences are, however, doubtless those of season. 
This species can be readily distinguished from its nearest allies, S. 13-lineatus and S. spilo- 
soma. The ground color of the former species is darker, and the alternating stripes and lines of 
spots are unmistakably different ; its tail is shorter and less bushy, while the hairs are dull 
whitish or yellowish white, with only one median broad bar instead of two. In the skulls 
there is a very close resemblance. From S. spilosoma it differs by its more acute muzzle, the 
much greater distinctness of spots, more conspicuous ears, longer and fuller tail, its hairs 
having two bars of black instead of one bar, which at the tip extends to the very base. The 
skulls of the two are very different, in the much shorter and more convex form of the latter, &c. 
In Captain Pope’s collection are several specimens from the Pecos river, which may be con. 
sidered as the most northern limit yet recorded for the species. They are duller than those from 
the Rio Grande, the fur being in very old and ragged condition, probably just about to be 
replaced by new. 
This is probably the species to which Erxleben gave the name of Sciwrus Mewxicanus in 1777. 
It was first accurately described by Lichtenstein from a specimen collected near Toluca. How 
much further south it extends I am unable to say. The Rio Grande appears to be nearly its 
northern limit. 
List of specimens. 
3 Measurements. 
2 15 
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Eg he BS Locality. When col-| Whence and how Natureof|., |» Jo Jo |e |e he Collected by— 
BE js2|& lected. obtained. 5 specimen.|2 |S | iS 3 1B |S ests ale 
2 = os 6 BOJF EIR RR S| ge iesics 
2 (2°| 2 3 Bly Sls Sle dle Slegicclee 
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o |O0 wn is) BF fF BR & Fe eR 
518") 1652 | ....| Pesquieria Grande,Mex.| May, 1853] Lt. D. N. Couch...| 203) Skin ....|....[eee-|----[eeeeleeee/eoee|evee[LsD0| evcccceseseessescs 
2A0 |...... O | Matamoras, Mexico....|....0.. «..- nope wsDOrsicans vqaces wees [eedOre seen caval pana} > ucciusan|scealeeus|occs|eces|s ops p=snisephipyneiie 
ADSL) scees seeslececvees O.. cesevvcccceclcceecvcscccsleccces Os. sece eevee +ee| Inaleo’l,| .84/1.60 1.90/7.523.€35.50, .95)1.65) Dr. L. Berlandier. 
2499 |...... Seccleces 2e-GOrcccccccncucer|enseoneesces|sccece GO.. acccccccccles » lacOracnas +83) 1.65)1.95)6.98)....) e000) .95/1.50)....dO....ecevees 
2500 |...... Sens) senesnss GO. cececccccccslosecccsceceecleocone dO... ccecceceee cee [oedOcs cee. 80/153} 1.90/6.80)...0)eeme! o95/1.55} .00.dQee.s cenevses 
2501 |...... main Mw a s'acepine GO.. ceccvceveves|rcccanencscs|ecsece MOcs aha sine te cece |e edOre ceee -59/1.10/1.30/3.10 2,002.30 +63)1.00) .04dO.. 2000 sone 
2502 |...... Sahil sed anan's dO. cevvcvcccves|coscccceccccleccess dO.. sees veces eves |e dOsccoee +55}1.10)1.30/3. 10,2. 002.30 283) .93)...edOr..cccveeree 
352 | 1425*| ....| Brownsville, Texas ....| Feb., 1853 |...+++ dO... esevescees wooo] SKIN .oee| eee] oeee lee es /8.504.505.75)..../1.62).... ccecseeeeccee 
140 | 1267 | © | Bagle Pass, Texas.....|......0 1852 | Maj. W. H. Emory,|.... |..d0.. +... She eas bea | evil Deer viss| ss cul esaulanacsoeeepeceeeaee 
NGS) AUR lees wheats mained Gs. seccewiccveee| ceeeesns 1852 |. .s00- dO... cececcess[eces |..do adaeas seeeleeee|eees/8.504,255.20)..../1.50) ArthurSchott.... 
Be Bl ip bbb Ra secre ery GO.n osec cose wees |e aasenss TE5D || A noe. WO... ceeeveccce|sves JecBOvaaces ewasfones +144|8.25/4.25 «0 00}ooes[1.25/000edOreeseeee vere 
Rol lo vautllakadl| POLOM pewgssy. sceoedese| <saautas 1853 |...... GO., vcceccscen|evss jos GOs. cc00| cccc|scccleceolecns| oe Jaceefesiee/Le4o) Joie Oli Kssnuviae 
bd Cl a an sis] WUWERLEIT “COBRA ic ais sdvi| selec c0ctebants Capt. J. Pope......jevee oe 1G; ote vs coce) omen] eves [OcOU)snbb| seus |avsui Metal ecce oounesiaces Swe 
E746" eteaes ..-.| Pecos river, Texas..... May 14, °55|...... MOccsveisssbny Sl ..do...... wdec) soe] SUR eee 
2656 |...... cove) Fort Blissy.N. M ...vccrlcescscvsoees Dr. 8.W. Crawford.|.... Inalco’l,| .52)1.521.78 ea ey 1,02/1.65 .ccccccccessccceee 
' Eye dark brown; skin of feet white. 2 Skull 1.75 + 1.03 inches. 
