ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 225 



cephalic lobes are very richly supplied with nerves, they correspond 

 morphologically to the tentacles and to a large part of the head, and 

 they would seem to have the same functions. The olfactory organ is 

 to be found on the upper wall of the duct leading from the respira- 

 tory cavity to the exterior orifice which is placed on the edge of the 

 mantle. 



The genital gland is completely hermaphrodite, the same culs-de- 

 sac producing ova and spermatozoa ; at some distance from it its duct 

 becomes very tortuous and glandular, and secretes a viscous substance. 

 The efferent canal opens into the penis, while below there is the 

 delicate and long neck of the copulatory vesicle which always contains 

 a small central mass of brown material. The vaginal portion opens 

 below the right eye, not far from the point of attachment of the 

 mantle ; the male canal opens above the right eye. 



During development trochosphere and veliger stages are evident ; 

 particular attention is directed to the fact that the primitive form of 

 the shell is not at all patelloid, as is the case with Ancylus fluviatilis ; 

 the patelloid appearance is only secondarily acquired, and even then the 

 primitive whorls are still to be seen on careful examination. Various 

 criticisms of facts stated by Mr. Dall are scattered through the paper. 



Uropneustic Apparatus of Helicinse.* — H. von Ihering is of 

 opinion that the uropneustic apparatus is simple in the lowest forms 

 of the Nephropneusta, and that it is only within the limits of the order 

 that the differentiation into a respiratory portion (lung) and a renal- 

 efferent (ureter) has been effected. If this be true it is very highly 

 probable that the lungs of this division do not represent a modified 

 branchial cavity but a portion of the renal-efferent apparatus. The 

 absence of connecting forms forbids us from absolutely demonstrating 

 this, but all the facts of comparative morphology point to it. It will 

 be remembered that the author first enunciated these views in 1876, 

 and though his own investigations have led him to believe in them 

 more fully they have not yet met with general acceptance. 



Habits of the Limpet.f — J. E. Davis details observations made 

 on the feeding and sense of locality of Patella vulgata. 



By far the larger number of limpets live upon rocks whose 

 only covering consists of minute green algae and nuUipores, with 

 numerous acorn barnacles : those of the latter immediately surrounding 

 a limpet are invariably kept free from algae by them. The limpet 

 moves steadily on pretty much in a straight line, and continually 

 sweeps its elongated snout from side to side, feeling probably for 

 suitable patches. Those limpets which live near large seaweeds, 

 such as Fucus, feed extensively upon them. They do not feed when 

 covered by water, but always settle down firmly before the tide 

 rises. 



It was proved by marking individuals and their scars that every 

 limpet has its fixed home to which it returns before the rising tide 

 reaches it. The greatest distance at which a marked limpet was 



* Zeitschr. f, Wiss. Zool., xli. (1884) pp. 257-83 (1 pi.), 

 t Nature, xxxi. (1885) pp. 200-1. 

 Ser. 2.— Vol. V. O 



