14 BULLETIN OF THE 



convex flexuosities of the haemal valve pointed, not at the outer corners, but 

 nearer the median line. Area moderate, without any median line. Sides 

 not inflated. Neural valve channelled for two thirds of its length, with two 

 prominent rounded carina? corresponding to the flexuosities of the margin. 

 Apex very short and blunt. Cardinal process quadrate, long, abruptly re- 

 curved, like the blade of a hoe. Hinge plate longer than wide, anterior 

 point passing between and almost beyond the crura. The latter are longer 

 and more slender than in the previous species. Anterior ends of the lateral 

 loops nearly parallel, the widest part of the shelly lamina; being near their 

 posterior terminations, but the width of this part of the apophyses is nearly 

 uniform from one end to the other. Hamial arms of the apophyses diverging, 

 in nearly straight lines, from the hinge plate. Recurved part of the loop 

 proportionately much longer than in the two previous species ; neural 

 portion forming a regular ovoid. Visceral area very large, muscular im- 

 pressions reaching the middle of the shell. Soft parts mostly unknown. 



I have been thus explicit, perhaps more so than the subject requires, be- 

 cause the first two of our species have been united by Mr. Jeffreys, whose 

 opinion is justly entitled to weight, though I am forced to disagree with 

 him upon the present occasion. I consider septigera and Jioridana as two 

 well-marked and distinct species, in which opinion I have reason to believe 

 Mr. Davidson concurs. W. septigera and Raphaelis are more nearly allied 

 but the points of difference already noted are quite sufficient to distinguish 

 them, aside from the habitat and the fact that the adult Raphaelis is twice 

 the size of the largest septigera hitherto collected.* 



The greater portion of the mantle of W. jioridana is of the most ex- 

 treme tenuity and perfect transparency. It is furthermore so closely 

 attached to the shell as to render its removal intact — even with the aid of 

 acid — a matter of great difficulty. With this exception, the examination 



* In the specimen already alluded to, and regarded by Mr. Jeffreys as a transitional 

 form between septigera and jioridana, all the characters of septigera as above given are well 

 marked. It differs from the ordinary forms of septigera in being proportionately wider 

 than many of them, and in the sharper angles of the marginal flexuosities. But it is 

 noticeable that these last are not at the anterior corners, as is always the case in jiori- 

 dana, but are strictly within the anterior margin at some little distance from the anterior 

 corners, as is always the case in septigera. Hence I cannot admit that there is any tran- 

 sition exhibited in this specimen, but merely an exaggeration of the usual characters of 

 the species. The apophyses are missing. One of the other specimens of septigera, in the 

 same lot. fortunately preserved the ovaria, and I am glad to be able to state that they 

 differ entirely in form and extent from the same organs in W. Raphaelis. This is a good 

 character, though it varies somewhat, within certain limits. I must again thank Mr. 

 Jeffreys for the kindness which he has shown in forwarding specimens for examination, 

 — an example worthy of imitation by other naturalists, and well calculated to assist in 

 dispelling false impressions, and in adding to the accuracy of scientific work. 



