THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE IV. VOL. V. 



No. IX.— SEPTEMBER, 1898. 



oiaia-X3:Nr./^Xi JLiaTicniiES. 



I. — On the Discovery of Ctclosph^roma in the Porbeok 

 Beds of Aylesbury. 



By Henry Woodward, LL.D., F.E.S., F.G.S., etc. 



(PLATE XIV.) 



IN December, 1890, I had the good fortune to describe a new 

 SphEeromid discovered bj'' Mr. Thomas Jesson, B.A., F.G.S., in 

 the Great Oolite of Northampton, which I named Cyclosphceroma 

 trilobatum (see Geol. Mag., 1890, Dec. Ill, VoL VII, pp. 529-533, 

 PL XV). This specimen, which is redrawn on the accompanying 

 PL XIV (Fig. 1), is remarkable for its rounded outline, which 

 induced me to apply to it the name CyclospJicsroma. 



Great was my joy when, in March last, I received from my friend 

 Mr. E. J. Garwood, M.A., F.G.S., another Jurassic Isopod, of which 

 both the intaglio and the relievo had been obtained by him in the 

 Purbeck beds near Aylesbury. This remarkably beautiful Crustacean 

 proves to be a more perfectly preserved example of the same 

 Sphajromid which I had described in 1890, from the Great Oolite of 

 Northampton, and it needs but to compare Figs. 1 and 2 upon our 

 Plate to perceive that in Fig. 1 the thoracic segments are much 

 compressed together posteriorly, and that the hinder part of the 

 telson is wanting ; otherwise the resemblance between it and the 

 newly-found and much more perfect example from the Purbeck 

 beds of Aylesbury (PL XIV. Fig. 2) is unmistakable. 



A reference to the diagnosis of the genus (as given in Geol. Mag., 

 1890, p. 530) will show that it must now be amended in consequence 

 of the discovery of the more complete specimen by Mr. Garwood. 



CYCLOSPH^ROMA, H. Woodw., 1890 (emended 1898). 



General outline of body longer than broad in the proportion of 

 5 to 3. Cephalon trilobate one-fifth the length of body, rounded 

 and tumid, surface granulated ; eyes moderately large, cornea 

 vitreous, but facets of eye distinctly visible with a hand-lens; 

 thoracic segments seven in number, rather broader than the 

 head-shield or telson, with square margins, epimeral poiiion of 

 segments distinctly defined by a lateral line ; first thoracic segment 

 coalesced with cephalon and encircling the eyes ; segments of 



DECADE IT. VOL. V. NO. IX. 25 



