SUPPLEMENT.— WELSCHI A. li 



Note. — This is a very interesting species because, though the costse are present, 

 there are some obvious gerontic characters, namely, incipient excentrumbilication, 

 correlated slight inflation of whorl, greater convexity of periphery, decay of 

 carina, and shortening of rostration as shown by radial lines. The character of 

 the septa may also be gerontic. 



Locality and Stratum. — Dorset : Mapperton, near Beaminster, in a whitish 

 stone, near base of limestone beds. 



Date of Existence. — Scissi or Murchisonse hemera. 



XIII. Genus — Welschia, 1 S. Buchnan. 



(Type — Welschia ohtusiformis," sp. n.) 



Definition. — Platy-subpachygyral, angustumbilicate ; subdensisep- 

 tate, sublongi-angustilobate ; laterally subflexiradiate ; peripherally 

 subanguliradiate, subconvexi-fastigate, parvi-nonsepticarinate. 



Distinction. — From Cylicoceras, the radial line is more curved and 

 slightly more peripherally projected ; the mode of growth is different 

 — a small umbilicus is associated with thicker whorls, and the peri- 



phery is more tabulate. 



Fig. 10.— Rndial 

 lie of Wtlschii 



ohtusiformis. 



•1. Welschia obtusifoemis, 8. Buchnan. Plate I; Suppl., Plates IV, fig. 19; and 



XII, figs. 1—3 a (Type). 



1887. Ludwigia IMukchisonj:, Tins Monogr., PI. i. 



Description. — Platy-subpachygyral, angusti-gradumbilicate, costate. 



Notes. — The large specimen, PI. I, is just a trifle more umbilicate than the small 

 one. Owing to its preservation it has been very difficult to trace its radial curve. 

 The result given in Suppl., PI. IV, fig. 19, may not be exactly accurate. 



Mr. C. Upton has shown me a specimen from Chideock identifiable with this 

 species, and about the size of the figured type ; but it possesses only small costa? 

 in the inner whorls. It is, perhaps, a case of temporary arrested development in 

 youth. 



1 In honour of M. Jules Welsch. 



2 The type specimen of the genus is the one figured Suppl., PL XII, figs. 1 — 3. 



