Mr. E. R. Lankester on the Anatomy of the Limpet. 335 
4th. The form, size, and structure of the renal organ; its 
communications 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. ach 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 
eavity, 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 
