I'LIOMURA. 153 



Genus PLIOMERA, Angelin. 

 1. Pliomera sp. Plate XIX, fig. 16. 



Description. — Pygidium subquadrate, but widening a little posteriorly, truncate, 

 strongly convex, and bent down at the sides. Axis conical, reaching about five 

 sixths the length of the pygidium, gently convex ; composed of an anterior, rather 

 rapidly tapering portion, consisting of five well-marked rings, and of a posterior, 

 less rapidly tapering, non-annulated portion, of equal length, with pointed ex- 

 tremity and with one median pit near front. Axial furrows well marked. Lateral 

 lobes strongly bent down, consisting of five simple, regular, flattened, unfurrowed 

 pleura3 in close contact, corresponding with the axial rings, gently curved back- 

 wards, and ending in bluntly rounded points which project on posterior margin of 

 pygidium. Interpleural furrows sharp and deep. Pleural furrows absent. The 

 last pair of pleuras bend inwards, meeting and running backwards in contact 

 behind the axis, but separated from one another by a strong interpleural furrow. 



Remarks. — It does not appear that this genus has been hitherto detected in the 

 Girvan area ; but there are two specimens of pygidia from the Llandeilo of Auchen- 

 soul, and another from Tramitchel, which undoubtedly belong to it. One of the 

 Auchensoul specimens measures 8 mm., but the other only 3 mm. in length. 



This species differs from all other species of Pliomera (= Amphion auctt) 1 

 by possessing a long, posterior, non-ringed axial portion belaud the fifth axial 

 ring. In P . fischeri* this portion is much abbreviated, being no longer than the 

 preceding ring. But in the other characters of the pygidium the Girvan specimens 

 show a close resemblance to this species, the general shape and contour of the 

 pygidium being similar and the number of rings on the axis and of pleurge on the 

 lateral lobes being identical, and possessing the same features. The previously 

 described British species of the genus, P. pseudo-articulata (Portlook), 3 of which 

 the pygidium is known, is quite distinct, the fifth pair of pleurae being fused 

 completely with the non-ringed portion of the axis behind the fifth axial ring. 



Collection. — Mrs. Gray. 



Horizon and Localities. — •Stinchar Limestone Group (Llandeilo): Auchensoul; 

 Tramitchel. 



1 It lias recently been pointed out by Raymond (' Ainer. Journ. Sci.' [4], vol. xix, 1905, p. 377) 

 that the generic name Amphion was applied by Hubner in 1816 to a genus of Lepidoptera, while 

 Pauder did not propose the name for a trilobite (A. frontiloba = A. fischeri, Eichw.) till 1830. 

 Augelin's name Pliomera (1854) for A. fischeri, Eichw., and others of this type, must therefore !»■ 

 adopted in place of the pre-occupied name Amphion, Pander. 



2 Brogger, ' Die Silur. Etag. 2 und 3,' p. 135, pi. vi, fig. 3 a ; Schmidt, ' Rev. Ostbalt. Silur. Trilob .' 

 pt. i, p. 191, pi. xiii, fig. 8 a. 



3 Salter, 'Moil. Brit. Trilob.,' p. 80, \,\. vi, fig. 29. 



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