FOREGUT ANATOMY OF CRASSISPIRINE GASTROPODS 



87 



ture to use the tree as a basis for classification of the Crassispirinae. 

 However, foregut characters have potential for unravelling relation- 

 ships amongst the gastropods with rather similar shells. 



DISCUSSION 



Summary of anatomical variation in 

 Crassispirinae 



Considerable variation was found in the configuration of the foregut 

 amongst the species we studied. This variation is reflected in the fact 



that we have recognised 1 3 main types of crassispirine foregut (Figs 

 33-34), which differ in the presence, position and morphology of the 

 main structures, such as buccal mass, salivary glands, buccal lips and 

 sphincters of the buccal tube. 



Several features are characteristic for the vast majority of the 

 crassispirines and these include a glandular lining to the anterior part 

 of the rhynchodeum and the ability of the posterior part of the 

 rhynchodeum to evert during proboscis protraction (except 

 Crassispira harfordianaflucki - Fig. 33 Cj.This is recognised by the 

 continuity of the posterior rhynchodeal and proboscis walls. In 

 nearly all Crassispirinae, the oesophagus is elongated between the 



Fig. 33 Diagram summarizing some of the major types of foregut morphology found among the Crassispirinae. Not to scale. A, Crassispira (Crassispira) 

 spp. - with acinous salivary glands. Funa spp. - with single tube acinous gland. B, Crassispira (Gibbaspira) dysoni. C, Crassispira (Glossispira) 

 harfordiana flucki. D, Crassispira (Crassiclava) spp. E, Burchia new species. F, Crassispira (Striospira) tepocana. 



