aeters, and that it is necessary to extract and examine the genitalia 

 in order to separate them. The same is true of Porto Rican species, 

 especially as regards closely related species in either group. Of the 

 two sexes, the genitalia of the male are the more highly specialized, 

 and therefore of greater use in separating species. 



The genitalia of a male Phyllophaga may be described as a serai- 

 chitinous, tubular, protractile organ whose distal end, for about ont - 

 third of the entire length, is enlarged and modified into a collar, 

 or theca, which is parted longitudinally on tlie ventral side. The 

 tliet-a is articulated at the sides to the upper or proximal portion 

 of the genital organ, the dorsal suture being protected by a tym- 

 panum. The distal margin of the theca is nearly circular and 

 cuplike, concealing the fleshy phallus; the aucipital margins on the 

 ventral side are variously modified into corneous hooks or barbs. 

 In many American species of Phyllophaga, including such species as 

 horuii, ilicis and hipartita, the theca is greatly modified, becoming 

 articulated on the dorsal side and formed into two highly specialized 

 claspers. which are dissimilar in shape. In other species, such as 

 quercus, ruhiginosa and forhesi, the theca is bilaterally symmetrical 

 and more regular in shape, as is the case with Porto Rican species. 

 In none of the American species, however, is the phallus (which may 

 be known as the median lobe of the genital organ) highly specialized 

 as in the species of the Island. 



The median lobe of the male genitalia of Porto Rican species 

 bears, normally, a superior, deflexed, acicular process, or spicula. 

 which is roundly bent toward the right, and an inferior pair of adnate. 

 falciform armatures, which cross scissor-like at their bases and re- 

 cross, or at least meet, at their tips. (See PI. Y, figs. 6 and 7.) In 

 the group including the two species of smaller size (guanicana and 

 citri) the adnate armatures are fused into a single spatha, which 

 is in one case fleshy (guanicana) and in the other case chitinous 

 {dtri). In the group including the two larger species (vandinei 

 and port or ie en sis) the adnate armatures are distinct, chitinous. dark 

 brown and shining, the dextral armature superior and the sinistral 

 inferior; they are compressed or cylindrical at their bases and 

 depressed at the tips, which lie one over the other. The distinguish- 

 ing characters lie in the structure of the tips of these armatures, 

 which are bicuspidate in one {vandinei) and spatulate in the other 

 {portoricensis) . 



The female genitalia consist, in American species, of two pairs 

 of flattened plates, an inferior and a superior, the latter extending 

 beyond the former, and above the superior plates, at their suture, a 



67 



