No. 504] ORIGIN OF FROTH IN SPITTLE-INSECTS 



has been completely removed. These, which lie in about 

 the mid-pleural region, are somewhat pulvinate in shape, 

 but by no means regular in outline. 



As to the location of these glands there seems to be 

 some difference of opinion. Batelli (1901) describes 

 them as being located on the last two abdominal segments. 

 Misinterpreting Wheeler's (1889) account of the adeno- 

 podia of the first abdominal segment in embryos of Nepa 

 and Cicada, he erroneously homologizes these glands of 

 Aphrophora with such structures, but rejects Wheeler's 

 view that they are homologous with abdominal append- 

 ages. Porta (1900) and Gruner (1901) believed that 

 these glands are situated on the seventh and eighth 

 abdominal segments, while recently Berlese (1907) gave 

 as his opinion that they were located on the eighth and 

 ninth abdominal somites. I am of the opinion that Porta 

 is correct, for there is no evidence that the first abdominal 

 segment has been suppressed and they are clearly on 

 the existing seventh and eighth abdominal somites (Fig. 

 2). Morever, this would harmonize more fully with Ber- 



