FOREGUT ANATOMY OF CRASSISPIRINE GASTROPODS 



ire 



63 



Fig. 8 



Crassispira (Striospira) tepocana Dall, 1919. Semidiagrammatic longitudinal section of the foregut (salivary ducts and glands not shown). 



marginal teeth of the wishbone type (Fig. 1 la), with a solid, sharply- 

 pointed major limb and a shorter, slender, secondary limb. The 

 marginal tooth is long, ca. 175pm (1.1% of SL, 2.9% AL). 



Crassispira (Striospira) tepocana Dall, 1919 

 (Fig. 8) 



Rhynchodeum and proboscis 



The rhynchostomal sphincter is small and anteriorly located. The 

 epithelium of the anterior two thirds of the rhynchodeal wall is tall 

 and glandular, while that of the posterior one third is continuous with 

 the proboscis wall. 



The proboscis is short (about half of the rhynchocoel), coiled and 

 folded in its anterior part, becoming narrow towards the tip. The 

 muscles of the proboscis wall are better developed at the base. The 

 proboscis tip is not infolded. There is no anterior buccal tube 

 sphincter and the sac-like enlargement of the buccal tube is slight. 

 The anterior part of the buccal tube is very narrow. There is a very 

 small intermediate sphincter, which lies at a distance of about three 

 radular tooth lengths from the very narrow mouth opening. The 

 proboscis wall is thick, composing 25% of proboscis diameter at its 

 base, and about 16% in its apical part. The buccal tube wall is 

 medium-thick, making up about 10% of proboscis diameter. The 

 buccal lips are very small. 



Buccal mass and oesophagus 



The buccal mass is long and curved and lies posterior to the 

 proboscis, equivalent to about two thirds of proboscis length. The 

 oesophagus is elongated between the buccal mass and nerve ring and 

 forms a short loop. The epithelium bears very long cilia, which 

 occupy nearly the whole lumen. The duct of the radular sac is broad 

 and very short, whilst the buccal sac is virtually absent. 



Glands 



The salivary glands are medium-sized, with the ramified tubular 

 morphology. The histology of the venom gland changes abruptly 

 anterior to the nerve ring. The duct of the venom gland is narrow and 

 unciliated. The gland itself is very long and occupies a large part of 

 the body haemocoel. The muscular bulb is extremely large, with 



thick walls formed of two subequal layers of longitudinal muscle 

 fibres, divided by a connective tissue layer, with a much thinner 

 innermost layer of circular muscle. 



Odontophore and radula 



The odontophore is medium-sized, with paired, unfused subradular 

 cartilages, formed by a single layer of cells. The radula is illustrated 

 by McLean (1971, fig. 66) and consists of marginal teeth of the 

 wishbone type (similar to C. kluthi. Fig. 1 lb), with a large, robust 

 and pointed major limb and a thinner, secondary element which is 

 attached near the tip of the major limb. 



Crassispira (Striospira) kluthi Jordan, 1936 



(Fig. Mb) 



The foregut anatomy of this species is similar to that of C. tepocana 



and only the differences are listed below. 



The rhynchostomal sphincter is larger and located further to the 

 posterior. The rhynchodeum is entirely glandular with no change in 

 epithelium along its length. The proboscis is highly coiled. The 

 proboscis walls are very thin in the anterior part and are thinner than 

 in C. tepocana (about 15 % of the proboscis diameter). The buccal 

 mass lies within the proboscis base. The oesophagus is more greatly 

 elongated and coiled between the buccal mass and nerve ring. The 

 duct of the venom gland is very long and highly coiled. The radular 

 teeth (Fig. 1 1 b) have a large, pointed, major limb and a more slender 

 secondary limb which is attached near the tip of the major limb. The 

 marginal teeth are short, ca.90um (0.5% of SL, 1 .4% AL). 



Crassispira (Striospira) xanti Hertlein & Strong, 1951 

 (Fig. 9) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is large and anteriorly located. The 

 epithelium of the anterior half of the rhynchodeum is glandular and 

 arranged into high folds; posteriorly, this changes abruptly to a non- 

 glandular epithelium, which is continuous with that of the proboscis 

 wall. 



The proboscis is short, about half of the rhynchodeum length, 

 with the tip not infolded. The proboscis walls are thick, composing 



