160 PARTULA. 



Ferussacidce, Amastrida and Achatinellidce, all of which 

 have the kidney very long, far exceeding the pericar- 

 dium. For comparison I figure the pallial region of Ena 

 reiniana (Bidiminus reinianus Kob.), pi. 42, fig. 3, x 2. In 

 the genitalia, the Partulida are remarkable for the absence 

 of an appendix, the penis being simple. This organ is pres- 

 ent and highly developed in all the other families. The vas 

 deferens is practically free from the oviduct, its adhesions 

 being merely superficial. This is a somewhat unusual con- 

 dition, and where found it seems to be associated with vivip- 

 arous reproduction. The shell is rather characteristic; in 

 form some En-idce are similar, yet the spirally striate em- 

 bryonic whorls are unlike that family, and are an invariable 

 feature of Partulidce, though occasionally this sculpture is 

 lost by wear in adult or old shells. This is not in itself a 

 feature of much importance, yet so far as I know, there is 

 no other Bulimoid snail with an expanded or reflexed lip 

 which has spirally striate embryonic whorls. 



From these comparisons it will be seen that the Partulidce 

 stand somewhat isolated. There is no family of Bulimoid 

 or Achatinoid Orthurethra which can be said to be nearer 

 than any other to the Partidida, so far as present informa- 

 tion goes. 



Hybridism. 



In dealing with Society Island species both Mr. G-arrett 

 and Dr. Hartman have called attention to certain specimens 

 of intermediate character which they looked upon as hybrids 

 between species commonly considered to be distinct. Garrett 

 writes as follows: " Hybrids between P. elongata and P. 

 tceniata, and between P. garretti and P. thalia, are so com- 

 mon where those species come in contact, that I am inclined 

 to believe they possess a certain degree of fertility. I have 

 also detected several hybrids between P. faba var. subangu- 

 lata, and P. virginea ; one between the arboreal P. imperforata 

 and the terrestrial P. lugubris; two between P. lineata var. 

 strigosa, and P. tceniata ; about a dozen between the arboreal 



