1911.] 



NATURAL SCIENCES OF PHILADELPHIA. 



477 



Fig. 4. — 0. friabilis from Wyandotte, removed from the shell, showing pigmen- 

 tation of mantle. 



San Marcos, Tex. — The pedal lines are double as usual, the 

 deeper ones meeting in a curve over the tail. No distinct caudal 

 mucus pore is discernible in some alcoholic specimens, but the 

 margin is less deeply grooved near the end of the tail than elsewhere. 

 Other individuals have a simple slit. There are no specialized dorsal 

 or facial grooves. The mantle margin has a short right body-lobe, 

 but no shell- lobes. The sole is tripartite. All the veins and arteries 

 of the lung are outlined with black pigment, causing it to appear 

 much darker than the lung of Arkansas examples dissected. 



The atrium is excessively short, only 

 reaching through the integument. The 

 penis is stout and short with terminal 

 retractor muscle, inserted distally in the 

 lung floor. About in the middle of the 

 penis a long stout epiphallus enters. It 

 tapers distally into the vas deferens, and 

 near the end receives a very slender muscle 

 which is inserted in the connective tissue Fig. 5. — 0. friabilis 

 around the base of the penis. The vagina g"^ ^ f™ 

 is chocolate colored and much swollen with tail-pore 

 below. The spermatheca is very large, 



oblong, on a slender duct about as long as the vagina (PI. XXXVII, 

 fig. 2). The organs measure as follows: 



Length of penis about 6.0 mm. 



" " epiphallus about 15.0 " 



" vagina 8.5 " 



" " spermatheca and duct 13.5 " 



The jaw is pale yellowish-gray, with a median ridge and strong 

 projection, sides distinctly striate. 



