72 F. R. Cowper Reed — On Phacops Weaveri, Salter. 



■ In the case of the second figured example (fig. 3) from Horse-shoe 

 Parm, Salter's figure does not correctly represent nor do justice to 

 it. The shell is missing from the whole specimen. The axis is 

 very long and narrow, tapering very gradually, but owing to the 

 loss by fracture of a part of its anterior end, its length cannot 

 be measured accurately, and its left side also is hidden in matrix. 

 The first two rings, corresponding to the first (marginal) and second 

 ribs of the lateral lobe, are broken off, but there are 13 rings behind 

 and traces of a fourteenth, making 15 or 16 in all. There are 11 ribs 

 preserved on the lateral lobes, and these ribs are not sickle-shaped as 

 Salter's figure represents, but are simply and gently curved back ; the 

 first 10 correspond with axial rings, the 11th starting apparently from 

 the level of the I4th axial ring. That there were more ribs behind 

 is probable but uncertain, as this posterior portion of the pygidium 

 is imperfect. The interspaces or furrows between the ribs are rather 

 wider than in the other specimen, and each furrow expands some- 

 what at its outer end into a blunt, rounded termination, but does not 

 thin out as Salter's figure incorrectly shows. Near the outer ends of 

 the 2nd to 9th ribs there is a trace of a faint median impressed line, 

 fbut this " interlineation " does not show so plainly or extend so far as 

 Salter indicates. The border of the pygidium is very slightly swollen, 

 but not raised above the general level of the ribs, which pass into it 

 "without any demarcation. The width of the lateral lobe preserved 

 is 21 mm. ; the outer half is gently arched down, but the inner portion 

 is fl.attened and nearly horizontal. 



These two specimens may be referred to one and the same species ; 

 but this species must be considered distinct from the other form which 

 occurs in the Llandovery of Long's Quarry. They are both separable 

 from Ph. caudatus, as Salter pointed out (Dec. ii, art. 1, p. 7), by the 

 more numerous ribs [Ph. caudatus having only 6-8) and by the ribs 

 not being duplicate. Salter, moreover, remarks that the fact that 

 "the margin is equal all round and not expanded or mucronate at the 

 end " is another point of difference from Ph. caudatus, but this non- 

 mucronate character is only found apparently in the Long's Quarry 

 figured specimens, as we have seen that there is reason to believe 

 that the Horse-shoe Farm " larger form" was furnished with a mucro. 

 Indeed, from his attempt to combine in his definition the characters 

 of these two types of pygidia it results that Salter's description is 

 strictly applicable to neither in every detail, and confusion has thus 

 ensued. 



The differences between the typical Llandovery form of Long's 

 Quarry and the Ludlow (?) larger form of Horse-shoe Farm are that 

 the pygidium of the latter is relatively more elongate and pointed, the 

 posterior end is probably mucronate, the axis tapers more gradually 

 and has more numerous annulations, and the lateral lobes are flatter 

 and have more numerous (11-13) ribs upon them. It scarcely seems 

 possible to regard these differences as of less than specific value, and 

 the name Ph. Weaveri must be resti'icted to those specimens agreeing 

 with the type from the Llandovery of Long's Quarry. 



In his monograph (pi. iv, figs. 8, 9) Salter attributes to Ph. Weaveri 

 certain specimens from Marloes Bay, They are in a completely 



