PHACOPS. 23 



more probably the May Hill, formation. The Illcenus Barriensis, Spirifer plicatellus, and 

 other Upper Silurian species, occur with them. 



Locality. — Wenlock or May Hill group. Cahirconree Mountain, west side, Dingle. 

 [Mus. Irish Industry, B. 242, 243.] 



P. (Phacops) Musheni, n. sp. PI. II, figs. 7 — 12. 



P. parvulus, vix \-uncice longus, ovatus, Icevis. Glabella oblonga, hand inflata, 

 superne urceolata, postice contracta, lobis basalibusprofunde scriptis bituberculatis, reliquis 

 connatis lineisque angustis modo sejunctis ; sulci mediani breves, curvi ; superiores fracti. 

 Lobus frontalis transversus oblongus. Thorax axe convexo ut pleuris lato, his lente recurvis 

 fulcro prope axin posito, sulcoque pleurali angusto distincto brevi. Cauda semiovalis 

 convexa immarginata, axe prominido distincto pauci-annulato, lateribus 3 — 4-sulcatis 

 abbreviatis angustiori. 



A much smaller species than the true P. Stokesii, with which it has been very generally 

 confounded. Nevertheless it differs by several important particulars, the chief of which is 

 that the shape of the head is long instead of broad, and the glabella decidedly oblong 

 instead of broad-triangular. The other portions, body and tail,— also differ ; the axis 

 of the body is broader, and that of the tail much more prominent, while the tail itself is of 

 a longer shape, less transverse. 



The length is seldom more than three fourths of an inch. The head in good specimens 

 is half a broad oval (that of P. Sto/iesii being a semicircle). The glabella is much 

 more than one third the whole width, oblong, only rather broader above than at the eyes, 

 and is urceolate, the sides bulging out between the eyes, and then contracted for the 

 hinder portion. The glabella is not at all inflated, nor does the front overhang in any 

 sense, and the facial suture is not even quite marginal in front. 



The eyes are fully half the length of the glabella, and very large and convex, not 

 depressed above, about as deep as they are broad, and containing nearly 130 lenses. These 

 have no visible spaces between them. The eyes are not very prominent, and on a 

 side-view appear sunk, especially towards the front, into the cheek. They vary a little 

 in size and prominence, but not very much so. 



The body has a rather convex axis, which is as broad as the sides, or nearly so. The 

 pleurae are curved down gently at the fulcrum, which is at about one third anteriorly and 

 less behind. The pleural groove is narrow, and reaches but little more than half-way along 

 the pleurae. 



The tail is longer than semicircular, very convex, smooth, with a prominent axis (not 

 flattened as in P. Stokesii), and reaching fully four fifths the length. It is long, conical, 

 ringed above, and smooth towards the bluntish point ; the sides are smooth, the three or four 

 faint lateral furrows not reaching half-way over the convex limb, even in the upper portion, 



