1915.] NATURAL SCIENCES OF PHILADELPHIA. 373 



As we searched the range carefully for OreoheUx after finding one 

 on the first day, it is probably extinct, not surviving the destruction 

 of the woods. There remains a possibility that it may survive in 

 some part of the mountains not covered by our collecting stations. 

 Thysanophora hornii (Gabb). 



Stations 2, 3, 6, 6^, 10, 11, 18, all in the limestone region north 



of Tweed Canyon. 



UROCOPTID^. 



Holospira is rarely if ever found on igneous or metamorphic rock; 

 and as the Dragoons are traversed by many dykes, the limestone 

 areas where Holospiras live are divided by tracts barren of these 

 snails. This has resulted in the differentiation of several species 

 which though variable do not intergrade, so far as we know. In the 

 Hacheta Range the limestone is continuous, and while there has 

 been a good deal of differentiation, the several extreme forms are 

 connected by those intermediate in structure and location. 



It must be admitted that our knowledge of the Dragoon Holospiras 

 is fragmentary. The whole foothill region, where they abound, 

 needs attention. They are easily found, and in large numbers. 



Holospira danielsi n. sp. PI. XIV, figs. 1 to 3a. 



The shell is cylindric, the upper fourth (or third) tapering to the 

 slightly mamillar, obtuse summit. Tilleul-buff, becoming darker 

 towards the summit. Nearly 2| embryonic whorls are smooth; 

 then slightly retractive axial ribs appear, rather low and' delicate 

 on the first neanic whorl, after which they become strong, widely 

 separated, oblique (retractive) on the conical portion, still more 

 widely spaced and vertical on the cylindric portion of the shell, 

 where the summits of the ribs are more or less irregular from breakage 

 due to being in part hollow there. On the penultimate whorl there 

 are 13 ribs (more or less). On the last half of the last whorl the 

 ribs become closer (or many may be interposed). The whorls are 

 rather strongly convex, the last one tapering downwards, being 

 compressed below the periphery; base rimate but not perforated. 

 The last fourth of the last whorl is somewhat straightened but not 

 built forward beyond the level of the ventral face of the shell. Aper- 

 ture rounded-ovate. Peristome narrowly expanded except at the 

 upper outer angle, where it is simple and obtuse. The axis is rather 

 slender, subequal except at the ends. In the la.st part of the penult 

 and first part of the last whorl there is a strong, short, obtuse colu- 

 mellar lamella close to the base; a parietal lamella, much longer 

 and usually strong (and freciuently a smaller basal lamella). 



