ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 375 



Cypreea and others. A resemblance also tolds between the Aspidobranchs 

 (Jkaliotis) and the other prosobranchs in the arrangement of the stoma- 

 togastric nerve. 



In regard to the pedal nerves, too, transverse commissures, like those of 

 Haliotis, are found in Paludina, though few in number ; but in Cyclophorus 

 there may be as many as 15 in number : where also a zygoneurous condi- 

 tion is present. Hence this genus is more nearly allied to Paludina than 

 to Gyclostoma. 



Anatomy of Patella vulgata.* — Mr. E. J. Harvey Gibson has 

 published the first, or anatomical, part of a projected monograph on the 

 common limpet, in which he gives detailed accounts of the various organs, 

 incorporating the results of the investigations of his predecessors (which he 

 has, when possible, examined for himself), with those to which his own 

 studies have led him. 



After describing the external form, the little known and complicated 

 alimentary canal is dealt with ; on the palate and on the floor of the 

 pharyngeal chamber there are two plates which protect the subjacent 

 tissues from injury from the teeth of the radula; the intestine lies in 

 apparently endless coils, the dissection of which is attended with great 

 difficulty, not only because of the extreme tenderness of the intestinal walls, 

 but on account also of the intricate way in which the coils are intertwined, 

 and the intimate connection that there is between them and the liver, right 

 kidney, and connective tissue supporting these organs ; in only one out of 

 twenty limpets was the dissection complete, and the alimentary canal was 

 then found to measure more than fourteen inches in length, the whole 

 antero-posterior diameter of the animal itself being only 2^ inches. 



The circulatory system consists of a branchial vein with veinlets, a 

 heart and two efferent vessels ; the branchial vein cannot be distinguished 

 from a large lacuna, having no special lining of epithelium and its walls 

 being composed of connective tissue. The heart consists of a large, very 

 thin-walled auricle, and a ventricle which is practically a sponge of 

 muscle-fibres. The functional gills are, morphologically, processes of the 

 mantle, which, also, has a respiratory function ; the mass of the latter con- 

 sists of connective tissue and muscle, with large and small lacunar spaces, 

 and the structure of the gills is essentially similar. The author agrees to 

 Lankester's statement that the renal sac is practically a series of blood- 

 vessels covered by renal epithelium ; this epithelium is arranged in several 

 layers ; the lower cells are rounded or polygonal, and present a homogeneous 

 protoplasm crowded with granules of a light green or brownish tinge ; the 

 upper cells are much larger, and contain a number of vacuoles, and 

 are, further, ciliated ; the right is much larger than the left nephridium, 

 and there is possibly some difference in the chemical characters of their 

 secretions. 



The integument consists of two or three layers, according to position, 

 a layer of light pigment-cells being added to the layer of dark pigment- 

 cells and the layer of connective tissue in the region of the nephridia. 



Nothing in the way of glands, suckers, or spicules could be made out in 

 the foot. The nervous system is exceedingly complicated, there being no 

 less than eight pairs of ganglia ; of these the cerebral, visceral, and pedal 

 are alone of primary importance ; some of Brandt's statements as to the 

 origin of the visceral and recurrent nerves are corrected ; the account given 

 of the eyes agrees in nearly all particulars with that of Fraisse regarding 

 Patella cserulea. The two tentacles are the special organs of touch. 



* Trans. Eoy. Soc. Edinburgh, xxxii. (n.d.), pp. COl-38 (5 pis.)- 



