Note on Trilobites, dec. 



253 



two Truncatulinas, when examined by aid of the microscope, 

 was found to consist entirely of homogeneous matter ; but 

 the other presented a far different appearance. Its segments 

 or zooids, and their connecting bands, all appeared to be 

 enclosed in a well-defined membrane. Each segment was 

 nearly destitute of sarcode, and contained a highly refrac- 

 tive body, in which appeared, with the utmost distinctness, 

 a germinal vesicle or spot. I can regard this body only as a 

 true egg, which has been developed at the expense of the 

 sarcodal element of the segments, in many of which the repro- 

 ductive process is occurring simultaneously. Yet it may be 

 objected that the ova in the larger segments are greatly 

 larger than the young or original animals of Truncatulina. 

 In some animals, however, as in Spongilla, Gregorina, &c, 

 many individuals are produced from a single egg ; and it is 

 not improbable that a process of great division of the egg or 

 swarming may take place in Truncatulina, by which a great 

 number of animals may be produced from each segment. 



II. Note on the Occurrence of Trilobites in the Carboniferous Limestones 

 of Fifeshire. B j R. H. Traquair, Esq. (Specimens exhibited.) 



In the neighbourhood of St Andrews, Fifeshire, remains 

 of a trilobite (Griffithides mucronatus — M'Coy) are pretty 

 common in the shale overlying the thick bed of limestone 

 worked at Ladeddie, Wilkieston, and Newbigging, and be- 

 longing to the Carboniferous Limestone series. 



At each of these quarries the limestone itself is hard, blue, 

 and crystalline, and contains but few fossils ; but these, 

 consisting of corals, polyzoa, shells, and trilobites, are 

 abundant in the overlying shale, though generally in a very 

 fragmentary condition. This is especially the case at Lad- 

 eddie, and, combined with the soft and friable consistency 

 of the shale, renders it difficult to obtain good specimens 

 from that locality. At Wilkieston, however, the shale has 

 assumed a more firm and slaty aspect, and the contained 

 fossils are in a much better state of preservation. 



The trilobites occur for the most part in a very disjointed 

 and fragmentary condition, entire specimens with head, 

 thoracic segments, and caudal shield in apposition, being 



