Mr. E. R. Lankester on the Anatomy of the Limpet. 335 



4th. The form, size, and structure of the renal organ; its 

 comniunications with the exterior and with the pericardium. 



5th. The absence of the oviduct described by Cuvier, or of any 

 such organ. In this matter I can merely confirm MM. Robin 

 and Lebert. 



In working out these matters I have been most kindly aided 

 by my friend and teacher. Prof. Rolleston. On my showing to 

 him the capito-pedal orifices, and one or two other points, he 

 investigated them further with me, and has given much of his 

 valuable time and many suggestions towards confirming and 

 elucidating these and other structures. 



With regard to the capito-pedal orifices, it seems somewhat 

 extraordinary that they have not been noticed by those very 

 careful observers who confine their studies to the external cha- 

 racters of Mollusca. They immediately overlie the salivary 

 glands, and are often coloured with an orange-red secretion, the 

 origin of which is very obscure. The generative gland is in 

 direct communication with, or, rather, lies in, the cavity into 

 which they open ; and they may serve as genital pores. 



Of the salivary glands and crop I need say no more here. 

 Cuvier did not find either of them; and probably those who 

 have dissected Patella since have not directed their attention to 

 the digestive tract. 



The renal organ has never been properly described. It is a 

 very large sac spreading between the liver and the muscular 

 tunic or mantle, and in many parts dendroid or branching. It 

 has two orifices, one on each side of the anus, which opens on 

 the right-hand side into the open chamber formed by the exten- 

 sion of the mantle over the "head and neck^^ of the animal. 

 Cuvier only recognized one of these orifices ; and his error has 

 not been corrected. Each orifice is placed on a little yellowish 

 papilla, varying much in size and continuous with the substance 

 of the large anal papilla. The papillal orifice nearer the median 

 line is the smaller, and may be called the supraanal orifice; 

 whilst that on the right hand is larger, and may be called the 

 infraanal. These two orifices represent two renal organs, as in 

 Lamellibranchs. The supraanal organ is very small and abor- 

 tive ; it lies in the superficial curve of the rectum, and is con- 

 tinuous around that portion of the intestine with the large 

 infraanal or right kidney-organ. The orifice leads into a small 

 cavity, with reticulated walls of a compact brownish tissue, 

 perhaps contractile. The infraanal orifice leads into a great 

 crescent-like sac which curves round the whole liver-mass, ex- 

 tending under it on the right side over the muscular foot-disk, 

 but on the left side skirting the generative gland and termi- 

 nating at the left anterior corner ; it branches out dendritically 



