252 DIPHYES BOJANI. 



Ridges at apex 3, 4, 5. 



Number of specimens 3, 15, 32. 



The ridges in the latter class are two ventrals, two laterals, and one dorsal. 

 The individuals with four ridges at the apex, fall into two main divisions. 



1. The original ridges are dorsal, two ventral and one lateral, and the 



second lateral results from the division of one of the ventrals, 

 which is the left in eleven specimens, and the right hand one in 

 two. This is the condition in D. malayana, and in D. gegenbauri 

 (Lens and Van Riemsdijk, :08). 



2. The four ridges at the apex are the dorsal, two laterals, and one 



ventral; the latter divides into two ventrals which enclose the 

 ventral facet. This agrees with Gegenbaur's ('60) description of 

 D. steenstrupi. 



In the three specimens with only three ridges at the apex, there are a dorsal 

 and two ventrals, both of the latter branching, to form the two laterals. The 

 level at which division of the ridges occurs is variable, and often so close to the 

 apex that it is hard to say how many ridges there are at that point. Since the 

 three classes intergrade it is clear that the number of ridges at the apex is not 

 of specific importance, at least in D. bojani. 



On correlating this character with the presence or absence of wing-like enlarge- 

 ments of the upper third of the ridges, it proved that of twenty-one specimens 

 in which these were evident, twelve had five ridges, eight had four, and one had 

 three at the apex. There is, then, no correspondence between the two charac- 

 ters, and I may add that there is every gradation between individuals in which 

 "wings" are prominent (Plate 7, fig. 2) and those in which no trace of them is 

 to be seen (Plate 7, fig. 3). 



The size and form of the basolateral teeth also proves to be so variable that 

 I can not follow Lens and Van Riemsdijk in making it the basis for specific 

 determination. It can not be correlated either with presence or absence of 

 "wings," or with the number of ridges at the apex. In a general way the pro- 

 portional size of the lateral teeth increases with the growth of the colony. But 

 this is irregular. In the larger individuals the margins of the teeth are strongly 

 convex (Plate 9, fig. 1) in the small ones (7-10 mm.) concave. But there is 

 every possible gradation between the extremes. In this respect "D. gegenbauri,'" 

 " D. malayana," and " D. indica" show three successive stages, as they do in size. 



The degree of serration varies independently of the characters alread}- 

 examined, and therefore is of no more importance. Small specimens are usually 



