284 BRITISH GRAPTOLITES. 



zone of Gephalog. cometa. In the Lake District it occurs in Marr and Nicholson's 

 zone of Moifiog. conoolutus, which occupies a corresponding systematic position. 

 Its common associates are Monog. gregarius, M. convolutus, and Glyptog. tamariscus. 

 Collections. — Sedgwick Museum, British Museum (Natural History), Lap worth, 

 and the Authors. 



Petalograptus (?) phylloides, sp. nov. Plate XXXII, figs. 16 a — e. 



Polypary very small, foliiform, not exceeding 5 mm. in length, and with an 



average breadth of 2'5 — 3 mm. Sicula very long, virgella conspicuous, 



first theca growing downwards for greater part of its length. Thecaa of 



the general Phyllograptus type, varying both in size and direction of growth 



in different parts of the polypary. 



Description. — The polypary and general characters of the thecse in this dwarf 



form strongly resemble those of a small Phyllograptus, but there are only two 



stipes instead of four. The polypary is in general twice as long as wide, though 



there is some slight variation in this respect. 



The sicula is extremely long, and in all young stages projects distally beyond 

 the polypary; it measures fully 3 mm. in length. Th. I 1 arises from near the 

 apex of the sicula (as in Phyllograptus), and grows downward for the greater part 

 of its length, apparently bending slightly upwards in its apertural region. Th. I 2 , 



th. 2 1 , th. 2 2 , and th. 3 1 all grow horizontally, and 



Figs. 196 a and &.— Petalograptus (?) ° . 



phylloides, sp. nov. o\\\y in the later theca? does the upward direction 



of growth become marked. 



There are commonly five or six theca3 on each 

 side, and the maximum breadth of the polypary is 

 attained with the development of th. 3 1 and th. 3 2 ; 

 thereafter with the change in the direction of thecal 

 growth the width diminishes towards the distal 



a ij ~ 



a. Young specimen, showing- sicula and extremity. 



earlier thecal Carrifran Burn, mi a i • £ ±1 j.i 



Moffat water; oienkiin shales! ^ lie apertural margins of the thecae are very 



ColUJeol. Survey of Scotland, Edin- slight ] y concave W heil COIlipreSSed, with their lower 



6. Younger stage (probably of same ec w s pro longed into sub-mucronate denticles. The 



species), showing sicula and th. I 1 o 1 o 



I96a th ' 1 * ° n same slab as Pig " tnec£e lire m contact throughout their length as in 



Phyllograptus. 



Affinities. — P. (?) phylloides has long been known in the Glenkiln Shales of 

 South Scotland, but has hitherto remained undescribed. 



It resembles a dwarf Phyllograptus or Petalograptus in its general shape, and 

 is here placed provisionally in the latter sub-genus for the purpose of reference. 

 But in the mode of development of its initial portion the polypary not only recalls 



