Dr, Ivor Tho)iias — Trilohite Fauna of Devon and Cornwall. 199 



Proetus, sp. a. PI. VII, Fig. 7. 



Description. — The elongated glabella has a lengtli of 8 mm. and 

 greatest breadth at its base of 5 '5 mm. approx. It tapers gradually 

 from the occipital groove to about the middle of its extension anteriorly, 

 where a slight constriction occurs. Thence the tapering continues 

 slowly to the rounded frontal extremity. The bounding furrows 

 enclose an angle of about 19° anteriorly. Three pairs of lateral 

 furrows are plainly discernible. The posterior pair curve backwards, 

 and are continued faintlj' to the occipital furrow, enclosing two sub- 

 rhomboidal basal lobes. The middle pair also curve slightly backwards, 

 but disappear nearly half the distance to the centre of the glabella. 

 The anterior pair are still shorter. The occipital ring, which is poorly 

 preserved, appears to have been fairly broad and elevated with a 

 narrow occipital groove. The head-shield terminates in a raised rim 

 of low curvature and separated from the frontal extremity of the 

 glabella by a fairly broad concave space. The facial sutures, of which 

 the left one is best preserved, cut the mai'gin of the head- shield ut 

 a distance from one another nearly equal to the length of the glabella. 

 They proceed backwards and slightly inwards from the frontal margin 

 to about the middle of the glabella, then become deflected in a short 

 curve outwards. The further course cannot be traced in consequence 

 of incomplete preservation. A part of the right cheek is preserved, 

 but is too poor for description. 



Locality and Horizon. — This fragment of the head-shield was 

 collected at the same locality and horizon as Ph. [Trim.) aff. cryptopli- 

 thalmus, Ph. {Trim.) tripartitus, sp. nov., etc. 



Remarks. — The glabella has a general resemblance to that of Proetus 

 dillensis, Drevermann, from the Upper Devonian Clymenien Kalk of 

 Langenaubach (3, p. 119, pi. xiii, fig. 9). The British form is much 

 larger, and differs also in the possession of the raised anterior rim and 

 a less regularly tapering glabella. 



Pkoetps, sp. h. PI. VII, Fig. 8. 



JDescription. — This pygidium is semicircular in outline, and has 

 a length of about 2'5mm. and greatest breadth of 4-5 mm. approx. 

 The axis is well marked, elevated, and tapers very gradually to a 

 blunt end posteriorly. About six fairly broad rings can be recognized. 

 The pleura, of which six can be seen, curve very gradually outwards 

 and backwards from the prominent groove bounding the axis. They 

 broaden slightly in their course to the marginal border, and are divided 

 into two well-marked portions by a narrow furrow. The two parts 

 appear to diverge slightly from each other as they approach the 

 margin. A well-developed flattened border is present, and is as wide 

 as the posterior end of the axis. 



Locality and ILorizon. — The same as the preceding form. 



Remarhs. — A certain resemblance exists with the figures of young 

 specimens of Proetus superstes, Parr., from etage G (2, pi. xvi, 

 figs. 4, 5). The axis of the latter is more tapering and the marginal 

 border is narrower. 



The above described form is probably new, but it seems inadvisable 

 to describe it as such without specimens of the head region. 



