NO. 14 



INSECT ABDOMEN SNODGRASS 



41 



mission are usually modified parts of the first, or the first and the 

 second, pleopods (abdominal appendages). In some cases, however, 

 the spermatophores are merely attached to the under surface of the 

 body of the female. Fertilization of the eggs takes place either within 

 the oviducts, or in a brood pouch on the under surface of the female's 

 body. A few examples of the external genitalia of the Malacostraca 



Fig. 15. — Crustacea-Malacostraca-Syncarida : male genitalia of Anaspidcs 

 tasmaniae. 



A, B, appendages of first and second abdominal segments, ventral view, show- 

 ing mesal processes, or gonapophyses (probably the endopodites), that compose 

 the intromittent organs. C, left gonopods, posterior (under) view, showing 

 functional relation of gonapophyses. D, ventral surface of last thoracic segment, 

 with gonopores. E, cross-section of testis. F, spermatophores. G, testis and 

 vas deferens. (E, F, G from Smith, 1909.) 



Endpd, endopodite ; Expd, exopodite ; lijon, 2Gon, first and second gonapoph- 

 yses (probably endopodites) ; Gprs, gonopores; NrCls, nutritive cells of testis; 

 Prtpd, protopodite ; Spc, spermatocytes ; Sps, spermatozoa ; Stn, sternum ; 

 T, tergum ; Tcs, testis ; Vd, vas deferens ; XII, XIII. XIV, twelfth, thirteenth and 

 fourteenth postoral somites. 



will suffice to illustrate the general structure and variations of the 

 organs in this group. 



The typical structure of the external genital organs of male Mala- 

 costraca is well shown in the Anaspidacea. In Anaspides tasmaniae 

 the male gonopores are two oblique slits on the venter of the eighth 

 thoracic segment (fig. 15 D, Gprs) situated on oval elevations between 

 the bases of the last pair of legs. The functional intromittent organs 



