342 The Laivrencian Formation, 



P. Islandicus inhabits the Atlantic from Nova Scotia to Green- 

 land. It occurs fossil at Beauport. Some of the- specimens are 

 four times the length of the one figured. Occurs fossil in Russia 

 and Sweden. Pecten^ a comb ; Islandicus, Iceland. 



Fig. 7. Naiica clausa. — This little shell is rather plentiful in 

 the deposit at Beauport, and is also found fossil in the Scottish, 

 Manx, Irish and north of England glacial beds. It is living in 

 the Arctic Seas and Gulf of St. Lawrence. At Beauport, numer- 

 ous specimens of Tellina and Mya may be collected, with small 

 circular holes drilled through them. According to Gould, (Inver- 

 tebrata of Massachusetts, p. 232,) these perforations have been 

 made by a Natica, probably this species. They are carnivorous, 

 *' andhav-e the power of perforating shells, it is generally supposed, 

 by discharging an acid which decomposes the shell, and through 

 the aperture they extract the juices, and destroy the lives of the 

 otherwise secure inhabitants. Their foot is large, so as completely 

 to envelope the objects on which they prey. In moving, they 

 burrow in the sand, so as to be almost entirely concealed by it, 

 and their place is generally indicated by a small heap of sand." 

 Natica, probably from nato, to swim or move with a fluctuating 

 motion ; cldusa, from clausus, shut up or inclosed. 



Fio'. 8i Scalarid horealis. — Belongs to the celebrated family 

 of WentU-traps, once so highly prized by shell-collectors, that one 

 hundred guineas has been paid for a single specimen of a favorite 

 species,,, the Royal or Precious Wentle-trap, S. pretiosa. The 

 species of this genus live in from 7 to 80 fathoms in sandy mud. 

 S. horealis, living in the Arctic Seas; fossil at Beauport and in 

 Sweden. Scalaris, like a ladder ; horealis, northern. 



Fig. 9. Buccinum undatum. — May be recognized by the folds 

 that cross the whorls ; most prominent on the upper part of the 

 whorl It is also marked with " raised lines, from one-fifth to one- 

 tenth, of an inch apart, with minute intervening striae." (Gould, 

 p. 306.) In the fossil shells, the exterior often exfoliates so that 

 these markings cannot always be seen. The protuberance on the 

 left-hand side of the aperture in Fig. 9 does not occur on all the 

 specimens. This shell is also called Tritonium Anglicanum. It 

 once^ lived : in the Mediterranean, but, as well as il/ya truncata, 

 has become extinct there, — a fact of great geological importance, 

 as it proves that the sudden disappearance of a fossil from the 

 strata^ of, onov country is no proof that it may not be found in a 

 gihhar formation in another. 



