Reports and Proceedings — Geological Society of London. 141 



Petalograptus folium, His. ; P. palmeus, Barr,, and varieties latiis, 

 Barr., tenuis, Barr., ovato-elongatus, Kurck ; P. ovatus, Barr. ; 

 P., n.sp. ; Cephalograptus cometa, Gein. ; and C, n.sp. 



She concludes that Petalograptus has been derived from Ortlio- 

 graptus foliaceus, 0. truncatus having been a step on the way. The 

 latter form has an almost horizontal connecting-canal, so that the 

 first of the second series of hydrothecee arises at nearly the same 

 level as the first of the primordial series ; whilst, if the connecting- 

 canal became more oblique and the thecaa more concavely curved, 

 a form identical with P. palmeus would be the result. Further 

 changes would give rise to P., n.sp., and subsequently to P. folium. 

 When the first theca of the second series arises so late that the sicula 

 is entirely free on the side remote from that on which the first of 

 the primordial series arises, an important stage is reached, and the 

 form becomes a Cephalograptus. Such a form is furnished by 

 C, n.sp., which is in some respects intermediate between Petalograptus 

 and Cephalograptus. The extreme form is reached in C. cometa, in 

 which the first hydrotheca of the second series is still later ; the 

 hydrothec^ are still longer than those of earlier forms and almost 

 parallel to the long axis of the rhabdosoma. The other known 

 forms of Petalograptus may have been derived from P. palmeus. 



It seems exceedingly likely that the Petalograpti had a Phyllo- 

 graptus as a remote ancestor, but the evidence for this is not yet 

 complete, nor can the author state whether Cephalograptus had a 

 further stage in the form of Dimorphograptus. 



2. " On some Superficial Deposits in Cutch." By the Rev. J. F. 

 Blake, M.A., F.G.S. 



The author arranges the deposits of which be treats under the 

 following heads : (I) Subrecent Conci'ete ; (2) Boulder Beds 

 associated with the former; (3) Quartzite Reefs; (4) lufratrappean 

 Grits ; (5) Laterite ; (6) Alluvium and Raun. 



(1) The Subrecent Concrete consists of a calcareous, porous, 

 laminated sand with milioline remains, which extends to a height of 

 about 700 feet above the Rann, and has a discontinuous distribution. 

 The author gives reasons for regarding this as an geolian deposit, 

 partly derived from recent marine accumulation and blown inland 

 and uphill by the prevalent winds. 



(2) The Bonlder Beds are next described, their distribution noted, 

 and their occurrence with seolian deposits recorded. The author 

 argues that the aeolian deposits once had a greater slope, and acted as 

 carriers, so that, under the influence of rain, the stones from the 

 hills slipped to their present position! 



(3) The Quartzite Reefs are described as filling up cracks ; the 

 material is of Eeolian origin and derived from the surrounding rocks, 

 and owing to this material having been formerly at a lower level 

 than the latter, water stood on it for a sufficiently long time to 

 permit of the materials being cemented by a siliceous deposit, and 

 converted into quartzite. 



