'ii'2 CONTRIBUTIONS TO CANADIAN PAL^EONTOLOIIY. 



apertui'e of the shell is not far fi-om civculai- iii outline, and in one 

 specimen the sutui-e appears to have been somewhat channelled. Adult 

 specimens have much the same shape as the recent BtoiiKiteUa imhriratit' 

 of Lamarck, l;)ut some which are not i|uite full grown have more the aspect 

 of a liiijiiretiix. 



This shell is \ery similar, both in shape and sculpture, to the Ph'iiro- 

 toiiiiir'iit, Sii/(iri-/iif< of G. and F. Sandberger, Ijut as the slit band and e\ en 

 the lines of i;ri>wth of that species have nnvev been seen, its generic ' 

 position is (|uite uncertain. When that portion (jf this paper was pub- 

 lished in which the species of ]-'!eu)-otiiiii<irui are enumei-ated or described, 

 (pp. .312-31-1:) the writer was under tlie impression that the shell now 

 under consideration should be referr'ed to Cijchiiii'iiut or Pohj1n>])ix. 

 Pi-ofessoi- E. Koken (of Konigsberg, Prussia), who has since examined 

 the original of ligs. 4, 4a and b. on Plate- xli, is, however, of opinion that 

 it is a true I'h'iivdtinniw'iii, and a careful re-examination of the minute 

 growth liiK.'s (]f all the specimens has led the wiiter to form a .similar 

 conclusion. Professoi- Koken, in a lettei- to the writer, says that the 

 whorls of P. Sijjd ritii:< are more rounded and more inflated than those of 

 the present species, and the spire proportionately higher. 



The writei' has nnich pleasure in naming this shell in honour of its dis- 

 coverer. Dr. J. W. Spencer, now State (Jeologist of Georgia. 



PTEEOPODA. 



(S.) Hyolithes alatus. (N. 8p.) 



Plate 4(i, figs. 2, 3 and 4. 

 Shell large, attaining to a length of a little more than four inches, 

 nearly straight, except when abnormally distorted, which it often is, 

 narrowdy elongated and increasing very slowdy in thickness : sides brcjadly 

 alate at their base, the " dorsal " margin being produced on each side into 

 a laroad thin laminar expansion. "Dorsal" side much flatter than the 

 " ventral," slightly convex along the median line and broadly but shallowly 

 concave on each side : ventral side strongly convex but angulated and 

 obtusely subcarinate along the median line: outline of transverse section 

 triangular, with the latero-basal angles pi'odueed on each side into a 

 narrow projecting spur, the base of the triangle, with its two spurs, being 

 more than twice as broad as the triangle is high, and each of its sides 

 faintly convex. Shape of the aperture not clea.rly ascertainable, though 

 on the dorsal side there is a broad and ratlier deep sinus, which is nearly 

 flat at the bottom, in the middle of the lip, and a projecting lobe, which 

 is broadly rounded nn its inner m.'irgin and narrowljr rounded or sub- 

 angular externally, on each side, as represented by flg. 3. 



