LEPTOGRAPTUS. 109 



The sicula has a length of 2 mm. or rather more ; it is broad at the base, l>wt 

 tapers somewhat quickly above the dorsal wall of the polypary. The first theca 



(tli. I 1 ) appears to arise near the apex of the sicula, 



Fn:. (>:i a. — Le tit oil ravins tlnrcittits, var. • , -. i ,1 j> j i • i 



spini/er, nov. a t a point 1 '1 mm. above the aperture of the sicula. 



Tli. V grows at first vertically downward until the 

 level of the sicula aperture is reached ; it then bends 

 Proximal end, shoeing apical origin of outward nearly horizontally and from it tli. I 2 is 

 ttecaii. Enlargement of pl xiv, developed, but in the reverse aspect of the polypary 

 the initial part of tli. I 2 and much of tli. I 1 are 

 concealed by the growth of th. 2 1 and th. 2 2 . The crossing canals are approxi- 

 mately horizontal, and the earliest thecas, generally three in number, developed on 

 either side of the sicula, have conspicuous spinal processes growing from their 

 apertures; these are as long again as the width of the stipe, so that while the 

 normal Avidth of the stipe measures *5 mm., when the spines are preserved the 

 total breadth is as much as 1 mm. 



The theca? number nine to ten in 10 mm., a number which appears to be constant 

 aol _ T _, , . ., at any point along the length of the stipe; their 



Fn:. (>.i h.-~ Lrptotjrnptns Jlncndtts, var. ■/ i. no r 



spini/er, nov. average inclination is about 1 5° or a little less, and 



they are in contact for about half their length. 

 Each theca has a length of about 2 mm., and the 



Distal theca;. Enlargement of part of , . , . . 



specimen on same slab as pi. xiv, aperture is somewhat narrow, occupying commonly 

 about one third of the length of the stipe. 



Affinities. — L. flaccidus, var. spinifer, is allied to another variety of L. fiaccidus, 

 var. macilentus, in the general character and form of its stipes. It differs in the 

 mode of origin of the stipes, in having spines on the proximal theca 1 , and a slightly 

 greater number of thecse in the same unit of length. 



Horizon and Locality. — Hartfell Shales. 



8. Scotland : Hartfell Spa. 



Associates, etc. — Var. spinifer occurs in the Hart fell Shales of S. Scotland, 

 approximately on the same horizon as the typical form, but its exact associates are 

 unknown. The best specimens, including the type, are in Lapworth's collection. 



Var. macilentus, Lapworth MS. Plate XIV, figs. 3 a— c; and Plate XV, 



figs. 1 a — C. 



Description. — A second variety of L. fiaccidus, named var. macilentus, differs 

 from the typical form chiefly in the greater rigidity of its stipes, their irregular 

 curvature, and in the characters of the proximal end and of the tlieca\ while the 

 length of the sicula also is somewhat greater. 



The stipes are characteristically rigid, but in some specimens their proximal 



