OGYGIA. 133 



Ogygia scutatrix, Salter. PI. XVII, figs. 9 — 13 (9, 10 are wrongly marked as 

 0. peltata on the plate). 



Ogygia scutatrix, Salter. In Siluria, 2nd ed., p. 53, woodcut 9, fig. 1, 1859. 



— — Id. Append. Ramsay, Geol. N. Wales; Mem. Geol. Survey, 



vol. iii, 312, pi. ix, fig. 1, and pi. viii, fig. 8, and plate 

 ix, fig. 1, 1866. 



0. septuncialis, fere rotunda ! vel latissime elliptica, depressa. Caput ? — . Thorax 

 Cauda brevior, axe lato ; pleuris longis axin \\ super antibus, prof unde sulcatis, a fulcra 

 {ultra dimidium posito) paullo deflexis. Cauda quam semicirculari latior, axe lato 

 8 — ^-annulaio ; limbo sulcis primariis 1 — 8, ad apices fractis ; secondariisrectisprofundis 

 haud axin attingentibus. 



I well remember finding this large specimen in 1853, together with the Asaphus affinis 

 hereafter to be described. They were on the face of a good slate fence in the valley 

 behind Garth, Portmadoc ; and were the harbingers and first fruits of the fauna, then 

 unexplored, of the Tremadoc Slates.^ The large size and round contour of 0. scutatrix 

 distinguish it easily from any other of the genus. The specimen is in the Museum of 

 Pract. Geology : it may have been a little altered in form by the pressure accompanying 

 cleavage ; but in the figure some allowance is made for this. If not sufficiently so, 

 still the form must have been a very wide and rounded one, and can scarcely ever 

 have had the shape of the species next described, although it is evidently closely allied 

 to it. 



Length 7 inches ; the breadth fully inches. Of the head we have only a single 

 specimen, in Mr. Lee's collection (fig. 10); and it is from a different locality and 

 formation. It appears to be very short and broad, with a wide urceolate glabella, a 

 broad striated margin, a small forward eye, and a wide labrum, with a narrow arched base. 



The body is four fifths the length of the tail, and of eight widely transverse joints, 

 with a broad axis, which is not convex, but sharply defined, and is more than two thirds 

 as wide as the flat pleurae. These are deeply grooved, the groove much curved at its 

 origin and bent (as are the pleurae) at the fulcrum-point. This occurs at about two 

 thirds out ; it is rather more remote in the front rings. The anterior or fulcral half 

 of the pleurae is much broader and less convex than the hinder part, which is angular, 

 almost gibbous, beneath the fulcrum. From this point a strong oblique striation covers 

 all the tips of the pleurae, corresponding to the broad- striated area which runs round 

 the tail-border. The tips of the pleurae are truncate, the hinder end produced a little 

 into an acute angle. 



* I am afraid I replaced the gate-post with somewhat insufficient material. A new Ogygia, and 

 that in a new and unexplored formation, was not to be resisted. The owner of the field must accept my 

 apology ; and will oblige me much by searching for more complete specimens. 



