320 SALIV-AHY GL.\XDS IN iL^RSXJPIALS, INSECTIVORES, RODENTS 



minal portion covered laterally by the greater sublingual gland and 

 duct. 



3. The greater sublingual gland (2) is an oval mass composed of 

 two di\-i3ions, each draining by a separate duct, which imite into a 

 single canal at the cephalic end of the gland. 



The greater sublingual gland is confined to the central portion of 

 the alveoUngual area, the caudal extremity barely extending beyond 

 the point of intersection of the submaxillar}' duct and lingual nerve. 

 There are no distinct lesser sublingual glands. 



As previously stated (cf. supra. Part I, p. 16), the structure of the 

 greater sublingual gland in this animal, and the absence of the group 

 of separate lesser subhngual glands, suggests that the latter have been 

 included in the building up of the double greater sublingual element. 

 In other words, Hydrochcerus may represent a t}"pe in which all the 

 available separate glandular components of the alveoUngual held are 

 appropriated in the development of composite larger glands -n-ith 

 separate ducts. A further unfolding of the greater sublingual element 

 might assign the value of a separate gland and duct to each of the two 

 components encountered in this form. In this case the alveolingual 

 area would, in the adult, present three distinct major glands, the median 

 submaxillary, intermediate greater sublingual, and a lateral element, 

 representing the usual group of lesser sublingual sprouts, united into 

 a definite gland with separate duct. Such a condition has not as 

 yet been encountered among the mammahan t\pes examined, but 

 Hydrochoerus forms an approach to its attainment. 



Two further examples of this form, contained in the Columbia 

 University Collection, both show the same composite formation of 

 the greater subhngual gland and the complete absence of a lesser 

 subungual group. 



Fig. 8. Hystrix Afric^-.\ustr.\lis — .-Vtricax Porcupixe. 

 Princeton University Morphological Museum, No. 1440. 



I . The parotid gland (5) is very large, extending from the subauricular 

 position cephalad aroimd the duct halfway across the masseter. and 

 caudad into the neck, increasing in breadth caudo- cephalad. Several 

 distinct lobules on the deep surface of the cephalic border come into 

 intimate relation w^th the submaxillar)- and greater subhngual glands. 



