628 SUMMARY OF CURRENT RESEARCHES RELATING TO 



througli which the thread-cells are sometimes found protruding. The 

 hepatic coecum occupying the greater part of the dorsal papilla reaches 

 nearly to the lower end of the sac containing the thread-cells, and in 

 several of these sections the authors saw a tube with muscular walls 

 leading from the base of the cnidophorous sac and opening into the 

 apex of the hepatic caecum by a small terminal aperture ; this last is 

 surrounded by a distinct sphincter muscle, so as to allow the lumen of 

 the hepatic caecum to communicate with the cavity in which the thread- 

 cells lie, and therefore with the exterior when the sphincter is relaxed. 



Anatomy and Development of Eenal Apparatus of Pulmonate 

 Gastropods.* — Herr T. Behme finds that there are some terrestrial 

 pulmonate Gastropods which have no secondary ureter to their kidney ; 

 such are Helix pulchella, Buliminus pupa, and others. The kidney, 

 however, agrees so closely with that of a Limnsea that we may assume 

 the great probability of their developmental history being similar. On 

 the other hand this history strengthens the view of von Ihering as to 

 the origin of the secondary ureter in his so-called Nephropneusta. The 

 kidney at any early stage of embryonic life opens with the primordial 

 kidney directly to the exterior ; later on it opens by a primary ureter at 

 the base of the lung-cavity into an open groove which passes to the 

 respiratory cleft ; this groove is formed by the walls of the pulmonary 

 chamber. The primary ureter becomes converted into the secondary 

 kidney, and, as the groove in the lung-cavity gradually becomes closed 

 from behind forwards, the ureteric apparatus is completely formed. 

 Helix pomatia which, so far as its ureteric apparatus is concerned, agrees 

 with the most highly organized Pulmonata, also exhibits during develop- 

 ment all the lower stages in the development of the excretory apparatus ; 

 these lower stages are retained throughout life in various other species. 

 We are, consequently, led to conclude that, so far as the renal apparatus 

 is concerned, the families and species with incompletely developed 

 secondary ureters remain at a lower grade ; the lowest is seen in those 

 forms whose kidneys are emptied by means of a primary ureter. 



The value of these characters from a systematic point of view can 

 only be tested when the comparative anatomy of other organs has been 

 made out. 



Reproductive Organs of Aplysiae.f — Sig. G. F. Mazzarelli describes 

 the anatomy of the reproductive organs in the Aplysise of the Gulf of 

 Naples. The hermaphrodite gland, large but compact ; the " small 

 hermaphrodite duct " varying in its details in different species ; the 

 albumen gland and the associated complex nidamental organ ; the 

 " large hermaphrodite duct " (vagina of Delle Chiaje, uterus of Meckel) 

 are described at length. The spermatic bursa is independent of the 

 vagina, and is in communication on one hand with the seminal vesicle 

 by means of the vas deferens, and on the other hand with the penis by 

 the spermatic duct. It is simply a second seminal vesicle. The 

 spermatic duct and the penis are then described at length. The 

 complex relations of the different parts are illustrated in a diagrammatic 

 figure. 



* Arch. f. Naturgesch., Iv. (1889) pp. 1-28 (2 pis.). 

 t Zool. Anzeiger, xii. (1889) pp. 330-7 (1 fig.). 



