THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE V. VOL. L 



No. VIIL — AUGUST, 1904. 



OK,IC3-II<r.A.l4 .A.E,TXCXjES. 



I.— Sedgwick Museum Notes. 



New Fossils from the Haverfokdwest District. II. 



By F. R. CowPER Reed, M.A., F.G.S. 



(PLATE XII.) 



Phacops (Dalmanites) socialis, Barrande, var. (PI. XII, Fig. 2.) 



rpHERE is one complete individual of a species of Phacops from 

 X the OrtJiis-argentea zone of Prendergast Lane, Haverfordwest, 

 showing certain interesting characters which make it worthy of 

 notice. The head is somewhat crushed and imperfect, but the 

 glabella is seen to be large and broad and to expand regularly 

 towards the front ; the frontal lobe is transversely rhomboidal and 

 nearly half the total length of the glabella ; there are three pairs of 

 lateral lobes, of which the anterior pair is the largest ; the second pair 

 is narrower, and the third pair is subequal to the second in size. The 

 first pair of lateral furrows is oblique ; the second pair is horizontal 

 and slightly arched forwards ; the third pair is slightly oblique and 

 the most strongly marked of all ; the occipital furrow is strong and 

 curved forwards in the middle. There is only a narrow median 

 strip of the glabella not crossed by the lateral furrows, for they are 

 rather long and all reach inwards to about the same extent. 



The thorax has a prominent axis about three-fourths the width 

 of the pleuree, which are bent downwards and backwards beyond 

 the fulcrum, which is situated at about half their length. Their 

 extremities ai'e slightly bent forwards and apparently rounded or 

 bluntly pointed ; a deep diagonal furrow traverses the whole length 

 of each pleura. 



The pygidium is nearly semicircular, with a regular rounded 

 margin, except behind the axis, where there is developed a long, 

 pointed, straight posterior spine, about two-thirds the length of the 

 pygidium. (In this specimen it is bent to one side, owing to 

 subsequent crushing.) The axis is about one-fourth the width 

 of the pygidium at its anterior end, and tapers rather rapidly to 



DECADE V. — VOL. I. NO. VIII. 22 



