Anatomical structure of Aspidogaster conchicola. 517 



originate in the ovary, just anterior to the testis, travel through the 

 tuba where they most likely meet with spermatozoa, pass the origin 

 of the Laurer's canal, take up yolk from the enormously developed 

 V i t e 1 1 a r i a, receive a covering from the shell-gland, are moulded 

 into their definite form in the ootype, and develop as they slowly 

 journey through the extraordinarily long, coiled uterus, the vagina 

 and finally the genital sinus to the exterior. Vas deferens and 

 vitelline ducts pass through the septum , but oviduct and Laurer's 

 canal are directed posteriorly below the septum, near the end of which 

 the latter terminates, but the former, curving round the end of the 

 septum, makes many folds above and down the sides of the intestine 

 and runs forwards to the genital sinus. 



The positions of the organs change with the contractions of the 

 animal. I have seen ovary and testis in some cases move from near 

 the anterior end of the foot back to the posterior end of the intestine 

 as the animal was striving to free itself under the cover glass. This 

 motion was permitted by the elasticity of the parenchyma and irre- 

 spective of any movement of the foot in a posterior direction. In 

 the compressed animal the disposition of the system as a whole may 

 take on very diiferent appearances. I have therefore prepared sections 

 of symmetrically hardened animals that were killed instantly under 

 hot sublimate etc. where presumably the organs had no cause to be 

 displaced. Of these, sections parallel with the surface of the ventral 

 sucker are very instructive, but for a continuous following out of the 

 system only the compressed living animal can suffice. 



VoELTZKOW has correctly described much of this system and in 

 those things I can only verify his statements. But chiefly with regard 

 to the structure of the bulbus, the significance of the Laurer's canal, 

 the structure of the vitellaria, the presence of a shell-gland and ootype, 

 and numerous exactnesses of position, shape and relations I have to 

 differ from his statements. 



Male organs. The testis (Fig. 16, 3, 11, 27, 22 T) is an 

 unpaired body of about 0,14 by 0,14 by 0,20 mm dimensions and is 

 situated slightly posterior to the middle of the infra- septal body- 

 portion. It is elliptical in surface view its long diameter corresponding 

 in direction with that of the animal. In sections is often seen an 

 indentation on one side as if bent, so that one may get sections where 

 the organ appears to be of a double nature. At first I thought that 

 perhaps we had here to do with a union of two testes, but having 

 twice found a rudimentary second testis (Fig. 22 T) I am convinced 



