730 SUMMARY OF CURRENT RESEARCHES RELATmG TO 



by the German embryologist. The internal end of the organ is very 

 difficult of detection among the mesodermal cells by which it is 

 surrounded; however, there appears to be an orifice which is pro- 

 vided with vibratile cilia, essentially similar to what has been seen by 

 Fol in the aquatic Pulmonata, and by Jourdain in slugs. 



The primitive kidney does not as in Bithynia (Sarasin) appear to 

 have any relation to the velum. The permanent renal organ seems 

 to be formed from an ectodermal invagination, and a mesodermal 

 growth. The author suggests that the pericardiac cavity is the 

 cavity of a somite, and that another is indicated by the primitive 

 kidney which is the excreting organ of the anterior, as is the 

 permanent kidney of the posterior somite. 



Nervous System of Parmophorus australis.* — M. Bontan de- 

 scribes the nervous system of the Gasteropod Parmophorus australis, 

 specimens of which were collected near Sydney, as being similar in 

 its main features to that of .Raliotis, as described by Lacaze-Duthiers. 

 The line of papillae between the foot and the first fold of the mantle, 

 is the homologue of the festooned border of the collarette of Haliotis. 

 This row of papillae forms part of the mantle, and cannot be referred 

 to the foot. The study of Parmophora, in which the nervous centres 

 are more separated than those of Haliotis, leaves no doubt in this 

 respect. 



Organization of Haliotis.! — H. Wegmann considers that Haliotis 

 has many points in common with the Acephala. Thus : — There is a 

 coecum between the stomach and the intestine. The digestive tube 

 is ciliated throughout its greater portion. There are the same con- 

 nections between the liver and the digestive tubes as in the Lamelli- 

 branchs. 



A series of organs, such as the renal organ, the auricle, and the 

 gill, are in pairs instead of being odd. Two rudimentary gills, with 

 the two that are developed, make up the four of the Acephala. The 

 cardiac ventricle is traversed by the rectum. Two arterial passages 

 arise from the two extremities of the heart. The venous circulation 

 is in its fundamental characteristics that of the Acephala, and the 

 position of the right renal organ between the branchiae and the system 

 is especially important. The structure and relationships of the renal 

 organs are essentially the same in the two cases. There is also a 

 remarkable simplicity in the genital apparatus ; a complete absence 

 of accessory glands and copulative organs ; and a singular connection 

 with the right renal organ, as in many of the Acephala. 



Absorption of the Shell in Auriculidae.l — Crosse and Fischer 

 illustrate and describe the peculiar absorption of the inner parts of 

 the upper whorls of the shell in this family, and also in the genus 

 Olivella. These animals appear to have the power of dissolving 

 entirely the internal partitions of the shell, from a point some distance 

 inside the aperture to the very apex. The only exception in the 



* Comptes Rendus, xcviii. (1884) pp. 1385-7. t Ibid., pp. 1387-9. 



X Journ, de Concliyl., xxii. (1883) p. 3. Cf. Science, ii. (1883) pp. 663-4. 



