c6 FDWARD DRANE CRABB. 



they held that the sex glands are separate organs instead of form- 

 ing an ovotestis. That is, they failed to recognize the dual na- 

 ture of the ovotestis. Since these observers believed the gastro- 

 pods to be unisexual they mistook some accessory organ for an 

 ovary or a testis. For instance, Wagner ('35) points out that 

 Cuvier, Meckel, Carus, Delle and others considered the albumen 

 gland as one part and the prostate gland as another part of the 

 testis in several gastropods, while Prevost and some others re- 

 garded the ovotestis as the testis and the albumen gland as the 

 ovary in a species of Lymn&a. Cuvier ('46) holds that in 

 Lymncsa and Planorbis the ovary and testis are separate, the 

 former sometimes being imbedded in the anterior part of the liver 

 while the latter is near the apex of the shell. Baudelot ('63) 

 states that Van Beneden, 1838, mistook the egg membrane gland 

 for the testis in L\mna;a glutinosus. Paasch ('43) called the 

 ovotestis a testis, and the hermaphrodite duct the epididymis in 

 Planorbis corncus, Lyinncea stagnalis, L. palustris, L. auricularium 

 and L. clongatiis. Simroth ('87) thought he found " pure " func- 

 tional females, i.e., individuals lacking the prostatic apparatus, in 

 Agriolima.v. The relative frequency with which he found these 

 " pure " females justifies the criticism of a contemporary investi- 

 gator, Schiemenz ('88), who states that Simroth failed to find the 

 male organ because one organ lies within the other. Hofmann 

 ('12) describes pathological and other abnormal conditions in 

 Helix in which various parts of the sex organs are wanting, rudi- 

 mentary, doubled or even trebled, but attaches no significance to 

 them. 



Wagner ('35, p. 104) appears to be the first worker to suspect 

 the true nature of the ovotestis in Gastropoda, while Baudelot 

 ('63) is the first to have given an intelligible description of the 

 finer anatomical relation of the parts of Lymnaa in that region of 

 the reproductive system where the hermaphrodite duct empties 

 into the definite male and female conduits and the albumen gland 

 duct empties into the uterus. 



This work was done under the direction of Professor A. 

 Franklin Shull, and the snails used were identified by Dr. Bryant 

 Walker and Mr. W. J. Clench. 



The two figures of the reproductive system of L. s. appressa 



