Renal Organ of Prosohranchia. 433 



tella vulgata) ," published in the 'Annals ' nearly fourteen years 

 ago (vol. XX. 1867, p. 334). The organs which I there re- 

 cognized as the " capito-pedal " orifices he now proposes to 

 identify with olfactory organs. With regard to this, I have to 

 say that I have long been aware that the " capito-pedal " 

 pigmented bodies are not orifices blocked by pigmented excre- 

 tion, as I at one time supposed 5 and I have no doubt, from 

 the nerve-supply to this region, which was clearly figured by 

 Prof, de Lacaze-Duthiers in vol. i. pi. iv. of his ' Archives 

 de Zoologie experimentale ' (1872), and is now again figured 

 by Dr. Spengel, that we have in the capito-pedal pigment- 

 body a sense-organ, similar in character to the sense-organ 

 described by Lacaze-Duthiers as existing in aquatic Pulmo- 

 nate Gasteropoda (also in vol. i. of his Archives, " Du sys- 

 t^me nerveux des Mollusques Gasteropodes pulmones aqua- 

 tiques et d'un nouvel organe d'innervation "). This last 

 memoir most unfortunately appears to have escaped Dr. 

 Spengel's attention, who endeavours to identify the capito- 

 pedal sense-organs of Patella with a rudimentary gill, and to 

 bring under the same denomination the often plicated proble- 

 matic sense-organs of a number of other Gasteropods. 



In discussing these homologies Dr. Spengel is led to ex- 

 pound his views on the torsion of the visceral mass of the 

 Prosobranch Gasteropods. His views are chiefly based upon 

 the fact, first made known by me, of the existence of two 

 renal organs in Patella. Dr. Jhering, in a memoir on the 

 morphology of the renal organ of MoUusca (Zeitschr. fiir wiss. 

 Zoologie, vol. xxix. 1877, p. 605), is the only observer who 

 has confirmed my description of the existence of two renal 

 organs in Patella ; and he has added similar observations on 

 Ftssurella and Haliotis. Dr. Spengel, in reference to this 

 matter, cites only the observations of Dr. Jhering, and omits 

 all reference to the fact that I had discovered the condition of 

 the renal organs of Patella ten years before that writer, 

 although Dr. Jhering quotes my observations at full length. 

 The fact has some importance ; for, as a natural consequence 

 of my observations, I have, during the period which has elapsed 

 since they were made, been in the habit of teaching the- 

 same general views as to the torsion of the visceral mass of 

 Gasteropoda and its effect upon the symmetry of the organs 

 as are now advanced by Dr. Spengel (explained by a woodcut 

 on p. 351 of his paper). This writer, to establish his views, 

 makes use of the fact first observed by me, but erroneously (and, 

 I do not doubt, unintentionally) attributes the observation 

 to Dr. Jhering. Speaking of organs which are paired though 

 not fully symmetrical in certain of tlie Prosohranchia, he says 



