346 BULLETIN OF THE 



and from the Western Atlantic, 



Cocculina Beanii Dull, Cocculina leptalea Verrill, 



Cocculina Rathbunl Dall, Cocculina conica Verrill, 



Cocculina Dalll Verrill, Cocculina splnigera Jeffreys. 



C. adunca Jeffreys is almost certainly the same as C. Beanii Dall. Tectura 

 rugosa Jeffreys, described with several Cocculina: under that generic name, is, 

 however, almost certainly a young specimen of one of the varieties of A cmcea 

 rubella. The specimens in the Jeffreys collection agree perfectly (although 

 dead and bleached) with specimens of A. rubella. 



Tectura galeola Jeffreys, which I examined through the kindness of Dr. 

 Jeffreys, is certainly not an Acmcea, as the long slope is anterior. In the 

 absence of the soft parts it must remain in a doubtful state, though possibly 

 a Cocculina. 



The discrepancies which have occurred in the description of the soft parts of 

 the different species would be somewhat difficult to reconcile, were it not 

 probable that this family contains more than a single group, on the one hand, 

 and, on the other, that the small size of the animals renders an examination 

 difficult and very liable to error of observation. 



Thus, C. spinigera has been reported to be without a rhachidian tooth. But 

 in several specimens of that species I found the rhachidian tooth (PI. XXXI. 

 Fig. 9) present, though very flat, translucent, and with only a trace of cusps, 

 which last, on the younger rows of teeth, would be absent, thus leading very 

 easily to a misconception. I have figured this tooth as observed by me in 

 specimens sent by Dr. Jeffreys. 



The observations of Mr. Watson on the gill of C. angulata I am not able to 

 accept as final, and believe that some misconception is mingled with them. 

 His description, and the position assigned to the supposed gill on " the lower 

 right side of the neck,' : correspond fairly well to the position and appearance 

 of the extended free ends of the anal and renal papillae in G. spinigera, organs 

 which, imperfectly observed, I strongly suspect to be responsible for the 

 alleged second and right-hand gill in Propilidium. I have never been able 

 to get a fresh specimen of Propilidium to determine this point, but the fact that 

 every known unfissured limpet with a free gill like that of Acmoza, whether 

 docoglossate or rhiphidoglossate, has that gill adjacent to the heart on the 

 opposite (left-hand) side from the anus, is ground for a strong presumption 

 that Propilidium and this particular Cocculina do not form exceptions to the 

 rule. 



The species of Cocculina may be divided into two sections characterized by 

 the presence or absence of posterior epipodial filaments. In the typical group 

 there are two posterior filaments. In the other there are none. 



The nearest relatives of this group are to be found in the Scutelliyiidce and 

 the Addisoniidre. It appears to be an ancient, and what Prof. Louis Agassiz 

 would have termed a " synthetic " type. 



