NO. 1483. 



UROCOFTID MOLLVSKS-BARTSCH. 



133 



by a moderately developed, spiral lamella, which extends feebly into 

 the first half of the last whorl anteriorly, and hardly reaches to the 

 antepenultimate posteriorly. The parietal lamella is one turn long- 

 and is chiefly located in the penultimate whorl, the very much atten- 

 uated anterior portion only extending partly into the last volution. 

 In its greatest development the lamella extends about halfway across 

 the chamber; the lamella is thin and decidedly outward curved in the 

 direction of the peripheral fold. Peripheral fold slender, a mere thread 

 extending- through about half a volution, situated about one-third of 

 the height of the chamber above the floor. Basal fold low, coextensive 

 with the parietal member. 



There are three specimens in the collection of the U. S. National 

 Museum, Cat. No. 175085, collected by C. R. Orcutt at Tomellin, 

 Oaxaca, Mexico. 



Measurements of Holospira [Iloluspira) oaxacana. 



« Type. 

 TRISTEMMA, new subgenus. 



Holospiras having three internal lamellae, i. e. , 

 an axial, a parietal, and a basal. 



Txj pe .—Ilolospira ferrissi Pilsbry. 



Two species belong to this subgenus, HolosinTa 

 {Tristem.ma) ferriHsl Pilsbry and Holospira (Tri- 

 stemma) pfeifferl Menke. 



HOLOSPIRA (TRISTEMMA) FERRISSI Pilsbry. 



The U. S. National Museum contains three 

 specimens, Cat. No. 189875, of this species, col- 

 lected by J. H. Ferriss at Manilla Mine, Huachuca 

 Mountains, Arizona. These are part of the 

 original lot and were donated by H. A. Pilsbry. 



Fig. 9.— Intekior view of 

 holospira ferrissi. 



a Specimen figured. 



