1882.] 'lightning' AND 'porcupine' EXPEDITIONS. 669 



more raised and oval at the sides ; under a microscope can be 

 detected numerous and close-set lines or striae, which are arranged 

 lengthwise : colour whitish : beaks none, except on the tail-plate, 

 where they are nearly circular : inside glossy. L. O'l, B. 0*05. 



* Porcupine ' Exp. 1870: Atl. St, 3 a, 17. Two specimens. 



Although this is a very small species, and might be regarded as 

 the young of some other species, I must observe that I have care- 

 fully compared both specimens with the young of all other European 

 species of Chiton known to me, and some specimens of which last 

 mentioned species are much smaller than those which I have now 

 described. The peculiar character of having so very few and scattered 

 tubercles is not presented by any other of those species. The girdle 

 is membranous and thin. 



9. Chiton marginatus. Pennant. 



C. marginatus, Penn. Brit. Zool. iv. p. 71, t. xxxvi. f . 2 ; B. C. 

 iii. p. 221 ; V. p. 199, pi. Ivi. f. 5. 



•Porcupine' Exp. 1870: Atl. St. Vigo B. 



Distribution. Greenland (coll. Moller, in mus. Copenhagen), 

 Faroe I., Norway to Mogador, Mediterranean and Adriatic, eastern 

 and western coasts of North America ; 0-40 fms. 



Fossil. Pliocene : Sicily (Monterosato). Post-tertiary : Norway, 

 Selsea ; 0-100 ft. 



C. cinereus of Laskey, Lowe, and Forbes and Hanley (not of 

 Linne), C. variegatus of Philippi and other authors, and C. dentiens 

 of Gould. 



D. Lophyrus, Poll. 

 Girdle imbricated or regularly granular. 



10. Chiton albus, Linne. 



C. albus, L. S. N. p. 1107: B. C. iii. p. 220; v. p. 199, 

 pi. Ivi. f. 3. 



'Lightning' Exp., St. 1, 2, 5. 



Distribution. Spitzbergen, Novaia Zemblia, Russian Lapland, 

 White Sea, Finniark southward to Isle of Man, Faroe Isles, Iceland, 

 Greenland, Wellington Channel, Behring Strait, eastern and western 

 coasts of North America; 0-337 fms. 



Fossil. Post-tertiary : Fort William. 



Family II. Patellid^. 

 «^ Patella vulgata, Linne. 



P. vulgata, L. S. N. p. 1258: B. C. iii. p. 236, pi. v. f. 3; v. 

 pi. Iviii. f. 1-4. 



' Porcupine ' Exp. 1869, St. Donegal B. 1870 : Atl. Gibraltar B. 



Distribution. Throughout the western coast of Europe from the 

 Faroe Isles and Bergen to Gibraltar, as well as the Mediterranean 

 and Adriatic; between tide-marks and even above high water, on 



