376 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The sexes are separate, the gonads single, and their ripe products are 

 poured into the cavity of the right kidney, whence they escape by the right 

 renal papilla ; the generative duct described by Cuvier has, then, no 

 existence ; Dall is incorrect in denying the presence in P. vulgata of the 

 "capitipedal orifices," while Spengel was wrong in regarding them as 

 orifices, for they are the vestigia of the lost true gills. Mr. Harvey Gibson's 

 experience does not tally with that of MM. Eobin and Lebert, who failed 

 to find the gonads in more than half the specimens they examined, for in 

 more than one hundred specimens collected at various dates he always 

 found the gonads, though they were sometimes small. 



Concretionary Gland of Cyclostoma elegans.* — M. P. Garnault refers 

 to the " glaude a concretions," which is found below the organs of Bojanus 

 in Cyclostoma elegans. Barfurth found that the concretions were of uric acid, 

 and, as such were wanting from the organ of Bojanus, he concluded that 

 the gland in question was the functional kidney. 



M. Garnault finds that the gland consists of numerous tubes collected 

 into tufts, and connected to the digestive tract by loose connective tissue, 

 while they are surrounded by a very rich vascular plexus, which can be 

 easily injected. In the adult, at any rate, the gland is without any 

 excretory canal. The concretions, when carefully observed, are found to 

 be absorbed. A prodigious quantity of bacilli are to be found filling up 

 completely the cavities of the tubes, and their presence is undoubtedly 

 normal. The author thinks that these bacilli contribute to the deposition 

 and the absorption of the uric acid, but he has not yet made the experi- 

 ments proj)er for determining this question ; notwithstanding the absence 

 of uric acid from the organs of Bojanus he believes that it is nevertheless 

 the true kidney, and suggests that the waste nitrogenous products may ba 

 excreted under some other chemical form. 



Osphradium of Crepidula.f — Dr. H. L. Osborn describes the osphradium 

 of Crejndula which appears to have hitherto escaped notice. In Cfornicata 

 it is represented by eighteen or twenty papilh'e placed in a longitudinal row 

 on a low ridge parallel with the gill ; each papilla has a globular expanded 

 head supported on a short narrow peduncle. The longitudinal axis of the 

 organ is traversed by a nerve-trunk which sends a branch into each papilla ; 

 the free ends of the columnar epithelial cells ajipear to be ciliated, and those 

 doubtless are sensory in function which are placed at the summit of the 

 papilla, where there is no distinct basement membrane, as there is on the 

 sides. 



A hitherto unnoticed area of peculiarly modified epithelium runs along 

 the ridge from which the gill-filaments arise ; this consists of very tall cells, 

 altogether unlike any other that are found on the mantle, and they are so 

 set as to form what appears to be a specialized organ. 



Terrestrial Air-breathing Molluscs of the United States.:}:— Mr. W. G. 

 Binney has published a second supplement to the fifth volume of his 

 'Terrestrial Air-breathing Molluscs of the United States and adjacent 

 territories.' It contains lists of the locally introduced species, the uni- 

 versally distributed species, and the Central and Pacific province species. 

 The most variable species found in North America appears to be Patula 

 strigosa, the geograpLical range of which is very great ; the various forms 

 are considered under the three heads of (a) shell transversely ribbed, 

 (/?) shell smooth or with rough striae, (y) shell longitudinally ribbed; 



* Coraptes Rendus, civ. (1887) pp. 708-9. 



t Zool. Anziig., X. (1887) pp. 118-9. 



+ Bull. Mus. Comp. Zool., xiii. (1880) pp. 23-48 (3 pis.). 



