PHILLIPSIA. 13 



PiiiLLiPSiA Derbiensis, Salter Sf Woodw. Cat. and Chart Toss. Crust., p. IG, 



fig. Ill, 1865. 

 — —II. Woodw. Cat. Brit. I'oss. Crust., ]>. 55, 1877. 



Glabella smooth, somewhat gibbous, in front ; sides nearly straight, with two 

 short furrows near the front of the eye, and a circular furrow around the basal 

 lobe at each posterior angle of the glabella; neck-furrow deep, neck-lobe rather 

 broad, with one small tubercle on centre ; fixed cheek very small ; facial suture 

 oblique, leaving a small angular portion attached to the neck-lobe on either side. 

 Eyes very large in proportion to head; reniform, smooth, but when well preserved 

 showing a fine and minutely-faceted surface. Facial suture uniting with outer 

 border of free cheek, and forming a very acute angle, where it joins the glabella in 

 front and a less acute angle behind the eye, where it unites with the posterior 

 border. A broad groove or furrow surrounds the free cheek running exactly 

 parallel to its own outer border ; the posterior angles of the head project slightly 

 backwards, but are not produced into cheek-spines. The incurved under margin 

 of the shield is finely striated as well as punctated. The hypostome (seen in situ 

 in one of our specimens, PL I, figs. 4 a, b) is large ; the mesial lobe is broad and 

 spatulate, the surface being finely striated with wavy longitudinal lines ; the lateral 

 lobes or alse are small, smooth, and pointed. 



The thorax, which is roundly arched, consists of nine smooth and well-defined 

 segments, the first only having a minute tubercle on the centre. The axis of the 

 thorax, which next the head is considerably broader than its side lobes, diminishes 

 gradually in breadth backwards to the pygidium, where it is only equal to its 

 pleuras in breadth ; the pleurce, which are smooth, are all faceted to enable the 

 animal to roll itself up into a ball. The axis of the abdomen, or pygidium, shows 

 it to be composed of thirteen coalesced segments, the pleurae being united in a 

 rounded shield, the border of which is smooth, as the ribs die out before they quite 

 reach the margin. There is a faint tendency to ornamentation on the axis of the 

 tail. 



Formation. — In Carboniferous Limestone, and in " Rotten-stone " band. 



Localities. — Bolland and Settle, Yorkshire ; Castleton, Derbyshire ; " Rotten 

 Stone," Matlock, Derbyshire; Longnor; Arnsidc; Blackrock and Little Island, 

 Co. Cork ; Middleton ; Carnteel, Tyrone ; Castlepollard, West Meath, and 

 Limerick, West of Dromore Wood. 



This is undoubtedly the earliest species of Carboniferous Trilobite recorded, 

 and is probably next in historical antiquity to the famous "Dudley Locust," 

 Calymene Blumenhachii, described by Lyttleton in 1.750, from the Wenlock 

 (Upper Silurian) Limestone. 



Fortunately we are acquainted with several perfect specimens of P. Derhiensis, 

 two of which are figured in our Plate I. 



