402 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



defined by a thread of calcite ; were it not for 

 that it would just look like a continuation of the 

 siphuncle of the large one, being in every way 

 quite proportionate. 



The next 2J inches contain three chambers (a 2, 3, 4) 

 filled with spar, except the middle one, which has 

 greystone on the outer half of one side. In the 

 first two of these chambers, the septum (d) is seen 

 to project for a short distance towards the concavity 

 of the preceding chamber, and in the next (a 4) has 

 surrounded the siphuncle (s) in a short tube. This 

 projection is not seen with any distinctness in any 

 of the other chambers, with the exception of the 

 seventeenth. Dr. Woodward's plate* shows this 

 shelly prolongation still more clearly. It is similar 

 to what is seen in the Pearly Naiitilus, where a 

 small tube projects into all the chambers. 



The fifth chamber has spar only on one side of 

 the siphuncle; the sixth is altogether filled with 

 spar; while the seventh has spar only on the outer 

 half of one side. The next five chambers are filled 

 with spar. 



The thirteenth is 2 inches in breadth and 1 in 

 depth, and is entirely filled with greystone, but on 

 the opposite side it is filled with spar to the extent 

 of one-half. The siphuncle (s) in this chamber is lined 

 on both sides with the thread of calcite, and this 

 white thread appears to enclose the siphuncle 

 throughout its entire length. The septum {d) of grey- 

 stone is well seen, being bordered with the thread 

 of calcite. 



Between the thirteenth chamber and the apex, 

 the siphuncle and the division into chambers become 

 gradually less distinct, as they are all filled with spar ; 

 but on being held up before the light, the trans- 

 parency of the spar, which also fills the next four 

 chambers, permits them to be seen, and that still 

 more clearly after wetting the part. In the three 

 following (a 18-20), the interior of the chamber has 



* Loc. cit. 



