from the Lias and Oolites. 877 



numerous fragments of others in the locality where it was col- 

 lected. The body-disc is large and pentagonal, it is composed 

 underneath of ten thin, delicate triangular plates arranged in 

 pairs, each pair forming a heartshaped shield, having an elevated 

 rugose carina down its centre, formed by the median element 

 of the ventral scutal plates which protrudes between each of the 

 two plates forming a pair ; the five shields are otherwise smooth 

 on their under surface, and were united together in the living 

 state by a membrane, but in the specimen before us they are 

 quite separate from each other ; at the apex of each of the ten 

 triangular plates a sharp toothlike process projects downwards, 

 which together form an imposing dental circle around the mouth - 

 opening. The rays are long, slender, and gently tapering ; we 

 have not been able to measure the absolute length of one, as 

 those which we have met with were always fractured ; the dorsal 

 median pieces of the rays are hexagonal and elongated trans- 

 versely, the ventral median pieces are elongated in the direction 

 of the length of the ray, and resemble the bodies of small ver- 

 tebrae which had been deprived of their neural arches ; the mar- 

 ginal plates are rounded and finely imbricated, their outward 

 free border is toothed with five or six pectinated processes, which 

 in the li^"ing state supported as many spines; the remains of 

 these are sometimes seen attached to their supports ; the 

 lateral scutal plates clasp the rays firmly and securely, and over- 

 lap the median pieces both above and below. 



Affinities and differences. — This elegant Sea-star somewhat 

 resembles in its general contour Ophioderma Milleri, but it is 

 distinguished from that marlstone species by having a propor- 

 tionately larger body-disc, with more slender and more tapering 

 rays : in the form and structure of the scutal elements of the 

 rays themselves there is likewise a difi^erence, those in 0. Milleri 

 are of a more elongated and regular form, whilst in O. Gaveyi 

 they are shorter, more ridgy and vertebrate-like ; the ten trian- 

 gular ventral discal plates are smaller in O. Milleri than in O. 

 Gaveyi ; they want likewise, in the figures given by Mr. Charles- 

 worth in the London Geological Journal, the toothlike spines at 

 their apices which are so characteristic of our Ophiura. 



Locality and stratigraphical range. — This Sea-star was col- 

 lected by Mr. Gavey from the upper shales of the Lower Lias 

 at Mickleton Tunnel near Chipping Cam})den, Gloucestershire, 

 whilst making the Oxford, Worcester and Wolverhampton Rail- 

 way; and we have found some fragments of a Sea-star much 

 resembling in structure this species in a Liasic bed of the same 

 horizon at Hewlitt's Hill near Cheltenham, during the excavation 

 of the new reservoir of the Water Works Company of that town. 

 We dedicate this species to our friend Mr. G. E. Gavey, whose 



