TAXONOMIC VALUE OF MORPHOLOGICAL CHARACTERS 25 



The dermal pores in this group are of three quite distinct types 

 which are represented in text figure 16. Of these types, one (fig. 16a) 

 is trilocular and more or less triangular in shape. Throughout this paper 



Fig. 16. Dermal pores of Pseudococcine forms : A, triangular type ; B, multilocular 

 type; C, quinquelocular type. 



it is spoken of as the "triangular type." Pores of this character are pres- 

 ent in all the species examined except one and occur for the most part 

 on the dorsum and in connection with the cerarii, although they may at 

 times appear on the venter as well. It is probable that the number of 

 these pores is more or less constant for each species, but, aside from those 

 occurring in the cerarii, it appears impracticable to make use of them. 

 They are too numerous to count and a very slight difference in the treat- 

 ment of specimens makes a marked difference in the visibility of the 

 pores and hence in their apparent numbers. The number of these pores 

 occurring in the cerarii, however, is of much significance. 



The pores of the other two types are circular. Of these types, one, 

 herein spoken of as the "multilocular type" (fig. 16b), occurs for the 

 most part on the venter of the abdomen and appears to be especially con- 

 cerned with the production of the ovisac. In a few species, notably in 

 certain of those herein referred to the genus Trionymus, these pores are 

 found upon the dorsum of the abdomen as well. Aside from this they 

 appear to present few possibilities of use. 



The third type, herein spoken of as the "quinquelocular type" (fig. 

 16c), occurs in but one species (Heterococcus arenae n. gen. and sp.), 

 where they entirely replace the pores of the triangular type. 



Body setae. The body setae, especially those of the dorsum, fre- 

 quently afford good specific characters. Their number, shape, size, and 

 distribution are all worthy of consideration. The ventral setae are much 

 less significant and I have not attempted to use them. 



Anal ring and anal lobe setae. In some species these afford fairly 

 good characters which may perhaps best be expressed in terms of their 

 actual length, and their relative length as compared with each other. 

 The actual length, however, is difficult to obtain with accuracy, due to the 

 fact that the setae are usually bent and for the purposes of this paper I 

 have made but little use of this character. 



