340 ME. WALTER WESCHE ON THE GENITALIA OF 



complete nomenclature for the genitalia of Diptera. Lately, P. du Rosille * has 

 demonstrated the value of a study of these organs, by distinguishing a number of species 

 in the difficult Sarcophaga geuvis that have previously passed as S. carnaria (Linn.), 

 by a comparison of the male armature. 



There are two papers on the male genitalia of Lepidoptera by P. Buchanan White, 

 M.D. t, and P. H. Gosse J; but these works are mainly engaged with the characters of 

 the outer and visible parts, with the view of determining species. There is no attempt 

 to dissect out the interior or to classify the armature ; but, nevertheless, the papers have 

 value, as they show, particularly in the beautiful drawings of Gosse, the endless variety 

 of shape and contrivance that may characterize any portion of the male armature. 



The male genitalia in Diptera always consist of a central tube, surrounded by more or 

 less complicated appendages. All these parts are extremely variable in shape and 

 in their relations to each other, but it will be seen that they homologize, though they 

 undergo very remarkable transformations. For convenience they may be divided into 

 four divisions : — (1) the posterior external valves ; (2) the anterior external valves ; 

 (3) the penis and its appendages; (4) the interior organs. 



(1) Posterior external valves. — The posterior external valves consist of the («) Porcipes 

 infericres and the (6) Porcipes superiores. 



(2) Anterior external valves. — The anterior extci'nal valves are the [c) Laminse 

 superiores. 



(3) Penis and apioendages. — In the third section are a number of organs beginning 

 with {d) the part of the penis, usually a hyaline membrane, which is the orifice and 

 continuation of the ejaculatory duct ; {e) the theca or sheath, which has ramifications 

 called by Lowne {f) the Paraphallus and {g) the Hypophallus ; {h) the Spinus titil- 

 latorius, [i) the Porcipes interiores, [k) the Palpi genitalium, and [m) the Apodemes of 

 the penis, often called, for the sake of distinction, the double apodeme. 



(4) Interior organs. — The interior organs consist of {n) the Ductus ejaculatorius, 

 (o) the Sacculus ejaculatorius, {p) the Pjaculatory apodeme, (/•) the Vas deferens, {s) the 

 Paragonia, {t) the Vasa efferentia, and (««) the Testes. 



{a) Porcipes inferiores. 



Structure. — These are a pair of more or less complicated hooks. They are on the 

 dorsal side of the abdomen in the Muscidae, but are laterally placed on the sides of 

 jDaired processes, the forcipes superiores, which are even more dorsal still, being on the 

 sides of the median line. Occasionally they have another hook articulated on to them 

 and are sometimes hairy, but generally they are structurally strongly cliitinized, with 

 setae and spines disposed in contact-areas. 



Nomenclature. — They correspond with the valvulse externse of Lowne ; they are also 

 known as zygapophyses or claspers. 



* Mem. Soc. Lianeenne du Nord de la France, Amiens, 1905. 



t " On the Male Genital Armature in the European I'hopalocera," Trans. Linn. Soc., ser. II. Zool. vol. i. (1876). 

 t " On the Clasping-Organs ancillary to Generation in certain Groups of the Lepidoptera," Trans. Linn. Soc, 

 scr. II. Zool. Tol. ii. (1882). 



