DORYMENIA PERONEOPSIS. 225 



into a deep pocket, which posteriorly develops a slit-like cavity functioning as 

 the outlet of the ventral salivary glands. In the mid line between the salivary 

 ducts the epithelium becomes more columnar and may function as a subradular 

 organ, as in Proncomenia hawaiiensis for example. A commissure from the 

 labiobuccal system passes in close proximity to it, but beyond this fact there 

 is nothing to indicate its function. The ventral salivary glands are long, tubu- 

 lar organs, about one eighth the diameter of the body in thickness, and contain 

 a lumen of unusually large size. The component cells, on the other hand, 

 are relatively small and are densely packed with granules staining a dull pink 

 after treatment with haematoxylin. 



The mid section of that portion of the pharyrrx posterior to the outlet 

 of the dorsal saUvary gland is the seat of the radula whose musculature and 

 relations to other organs are unique in this genus. In common with other 

 Glossophora the teeth are developed by clearly differentiated odontoblasts on 

 a well-defined basement membrane, and as far as can be judged from a careful 

 examination of cross sections number nine in each row. There are probably 

 not less than twenty-five rows. The median tooth is triangular with a base 

 whose length is approximately twice the height. Each admedian tooth is 

 Uke^vdse triangular with the base not over half that of the foregoing but with 

 a height fully as great. The lateral teeth are more spike-like, and Uke the 

 admedian are sUghtly twisted. These data, however, are largely derived from 

 the study of fragments and are doubtless incomplete. 



Beyond the narrow section where the fully developed teeth are fully exposed 

 in the pharynx the remaining portion, comprising fully half the total length of 

 the lingual ribbon, is bent backward and occupies the cavity of a large diverti- 

 culum of the pharynx ventral to the radula proper (Plate 7, fig. 5). As noted 

 presently this ventral sac is operated by several heavy muscles, whose relations 

 have been determined with a fair degree of accuracy, though their mode of 

 operation is not wholly clear. The position of this entire radular system in the 

 present specimen indicates that it is in a contracted state, and it is probable 

 that in the act of feeding the pharyngeal tube is not only widened considerably, 

 but that the radula is projected anteriorly borne on the summit of the ventral 

 diverticulum. This will become more intelligible after the muscles concerned 

 have been described. 



The entire outer surface of the ventral diverticulum is in contact with a 

 sheath of circular muscles of great thickness especially in the mid section (Plate 

 7, fig. 4, 6). This sheath is pierced at the bUnd end of the diverticulum by two 



