SUPPLEMENT. 167 



^vith a dark line, and thickly covered with pointed cirri of 

 various lengths and sizes, which are finely ciliated ; the longer 

 ones are very extensile, and sometimes curl and iinfold to a 

 length equal to half that of the shell : ocelli numerous, placed 

 more close together at the sides than in front, where they are 

 alternately large and small ; they look like globules of quick- 

 silver, or glistening pearls, or white coral beads set in rings of 

 dark bronze : foot finger-shaped, byssiferous, issuing from the 

 notch on the posterior side below the large ears of the shell ; 

 it is of a pale orangecolour. The animal occasionally uses its 

 foot for crawling. 



This variety is connected with the type by several inter- 

 mediate forms, as regards both the shell and soft parts. Dr. 

 Hidalgo ought to compare specimens from difi'erent localities 

 and depths. 



P. 64.— P. ARATTJS. N. of Hebr., 530 f. (C. & T.). It is the 

 P. Bruei of Payraudeau, a Mediterranean and Adriatic species. 



P. 65. — P. STJLCATUS. Mr. Hanley showed me a single 

 valve, said to have been trawled near the Runnelstone Light- 

 house off" the Land's End. 



P. 65.— P. TiGRiNus. N. of Hebr., 170-189 f.(C.&T.). R 

 Norway (Sars and others) ; Messina (Seguenza) ! E. HoUand 

 (Herklots) ; Brittany (Recluz and others) ; Arcachon (Lafont) ! 



p. 67.— P. Test.^. 



Body pale yellowish white faintly tinged with pink, mottled 

 with dark brown, speckled with flake-white, and barred trans- 

 versely with 8 or 10 irregular streaks of dark brown : mantle 

 fringed with fine tentacles of different sizes, which are deli- 

 cately ciliated and curl about in every direction ; they are ar- 

 ranged in two rows, the outer tentacles being much larger 

 than those forming the inner row ; the front edges of the 

 mantle are folded inwards, and appear to be microscopically 

 striated in the line of the opening : ocelli half as many only as 

 in P. striatus, and consisting of 2 rows ; those in the outer 

 row are unequal in size and irregularly distributed, one being 

 in many cases (but not invariably) placed at the base of each 

 pallial cirrus in that row ; those in the inner row are more 

 numerous, much smaller, and not always observable : foot 

 cylindrical : gills in 2 pairs, fan-shaped and exquisitely pec- 

 tinated, sometimes brownish or pencilled in the middle. 



It flits or jerks about actively, like its congeners, and oc- 



