212 PROCEEDINGS OF THE ACADEMY OF [1894. 



what more so in the young than in the adult; external sculpture of 

 small, somewhat irregular rounded riblets, with equal or wider inter- 

 spaces, each third (fourth, fifth or sixth) riblet being somewhat larger 

 and more elevated than the others and often duplex; of these larger 

 ribs there are twenty or less on each side; all the ribs are normally 

 rounded, and except where obviously broken by accidents due to 

 exigencies of growth, do not appear scaly or nodulous, though some- 

 times more or less keeled ; basal outline, apart from sculptural crenu- 

 lations, approximately oval, the anterior always narrower than the 

 posterior end. Lon. of shell 135; Lat. 112; Alt. 33 mm. The 

 distance from the apex to the anterior margin, horizontally, 63 mm. 

 "Some specimens are over six inches in length and proportionately 

 solid. The species seems to be one of the largest limpets known. 

 Although the nearest land is New Zealand, the shell has none of the 

 aspect so characteristic of the limpets of that region, but recalls 

 rather those of East Africa and the China seas. Patella patriarcha 

 Pilsbry, has much the same general aspect, though the sculp- 

 ture is wholly different. Putelln harbara L. has the discrepancy 

 between the primary and secondary radii much greater, and the 

 margin consequently stellate. The sinus near the anterior left hand 

 margin is not confined to this species but may be found in many 

 Patellidie; still, few species have it so strongly emphasized as in 

 P. kermadecensis. Its origin is doubtful, and can be cleared up best 

 by a study of the living animal. The larger specimens are usually 

 badly eroded, only the younger ones show the surface well, and the 

 islands (we understand from Mr. Fulton, from whom the specimens 

 were received) are visited but once a year. These circumstances 

 may account for the overlooking of so large a shell by untrained 

 collectors." 



Explanation of Plates. 

 Plate VII. 



(Illustrating Dr. W. H. Dall's description of examples in National 

 Museum Collection). 



Fig. 1. P. kentiadeceiisis, dorsal aspect. 



Fig. 2. P. kermadece)ims, ventral aspect. 



Plate VIII. 



Dorsal and lateral views of type specimen of /*. kmiKidecemis, 

 nearlv natural size. 



