333 



" It is not at all unlikely that the early volutions of H. Hornbyense 

 may be coiled indififerently to the right or left, and if so, that this may be 

 a mere sinistral variety of that species." 



In one of the types of //. Hornbyense, it may be added, the summits of 

 many of the ribs are curiously flattened downward, and this has since 

 been found to be quite a characteristic feature of the species. 



The foregoing descriptions refer exclusively to the spirally coiled por- 

 tion of the shell, the only part that was then known. Since they were 

 written, the writer has seen a few additional specimens of the species 

 from Hornby Island, the only locality at which it is, so far, known to 

 occur. Two of these, which are now in the Museum of the Survey, are 

 of special interest. One is a sinistrally coiled specimen, with a consider- 

 able portion of two and a half of the earlier volutions preserved, collected 

 by Mr. Harvey in 1895. This specimen, the original of figure 3 on Plate 

 42, has convinced the writer that H. pprversum is only a sinistral variety 

 of H. Hornbyense. The other, which is represented by figure 4 on the same 

 Plate, is by far the largest specimen that the writer has seen, and was col- 

 lected by Dr. Beadnell in 1895. It is also in the Museum of the Survey, and 

 is septate throughout. It shews that H. Hornbyense (like H. elongatum) 

 is at first spirally coiled, but that the calcai-eous tube of which it is com- 

 posed becomes free, deflected, and bent abruptly on itself somewhat like 

 the anterior and terminal end of a Hamites or Ancyloceras, before the 

 commencement of the body chamber. Unfortunately in this specimen (as 

 in that of H. elongatum figured on plate 12, figs. 1 and la of the second 

 part of this volume) the deflected part of the shell is completely broken 

 away and entirely disconnected from the spiral portion, so that, in each 

 case, it is difficult to get a clear idea of the exact shape of the shell 

 before it was broken. The tubercles on each side of the periphery or 

 venter, in this large specimen, are narrowly elongated, in a direction par- 

 allel to the ribs of which they form a part. A transverse section of the 

 deflected portion is nearly circular in outline, and the lateral diameter of 

 the aperture is a little over an inch and a half. Here and there small 

 portions of the septation are exposed, but in no place can a continuous 

 sutural line be traced. 



It may be that the spiral portion of the shell is more narrowly elon- 

 gated than was at first supposed, and that this species also may prove to 

 be referable to Hyatts' genus Bostrychoceras. 



