DELTOCEPHALUS DISTINGUENDUS. 61 



pygofer is at present obscure, and little would be 

 gained by assigning functions to such parts, upon the 

 few observed facts now at our disposal. 



Both Dr. Fieber and Mr. Edwards give some 

 description of the external genital apparatus of D. dis- 

 tinguendus. They chiefly relate to the angular forms 

 and the relative lengths of the plates and other parts 

 appertaining thereto. 



A review of the numerous figures I have already 

 given, of the genitalia of the species hitherto described, 

 will lead to the conclusion that the details have much 

 in common with the male parts of the Heteropterous 

 Hemiptera described in Dr. David Sharp's recent 

 suggestive and interesting paper on the Terminal Seg- 

 ment in some male Hemiptera (Trans. Ent. Soc. 

 London, part iii. 1890, p. 399). 



It will be well to defer remarks upon the probable 

 homologies of certain parts as developed in the two 

 families until the varied forms of the pygofers of the 

 Typhlocybidae come under description. 



Female. Almost immaculate yellow, with a vertex 

 browner than that of the male. The elytra often are 

 in this sex considerably shorter than the abdomen. 



D. distingiiendus does not appear in Sahlberg's 

 treatise of Cicadariae ; but in his diagnosis of D. pseiido- 

 ocellaris he says, " Vertice acutius producto, latitudine 

 sua basali et pronoto i longiore, medioquam lateribus 

 fere duplo longiore," &c. Also, he continues, " Grenis 

 extus obtuse dilatis — pronoto obsoletissime albido 

 vittato, "&c. (Sahib., ' Kapets, pro fauna et flora Fen- 

 nica,' p. 314). 



Mr. Edwards includes D. pseudocellaris amongst his 

 synonyms of D. distingiiendus, and I am inclined to 

 follow his lead; although, amongst my examples of the 

 latter insect, certain discrepancies occur, which do 

 not, however, appear to me of great moment. Both 

 the above authorities lay stress on what proportion 

 the height of the vertex or crown bears to the length 

 of its base ; and also on the outlines and curves of 



