206 ME. P. H. CARPENTER ON THE GENUS SOLANOCRINUS 



XIV. ACTINOMETRA CHELTONENSIS, n. Sp. (PL XI. fig. 20.) 



This fossil consists of the united radials and basals of what 

 must have been a very large Actinometra. The five basals are 

 united by their broader inner ends, so as to conceal the central 

 half of the radial pentagon (fig. 20b). A deep linear-oval groove 

 is excavated along the underside of each of them, terminating 

 just short of the rounded end which appears externally (fig. 20 a). 

 The sides of the groove are marked by very distinct cross ridges 

 and furrows, which do not quite reach either end of it. The outer 

 portion of the dorsal surface of the radials (i. e. that portion 

 which would have appeared externally when the centrodorsal was 

 in situ) is rather narrow, and looks almost entirely downwards. 

 Hence, although it appears on the dorsal aspect of the calyx out- 

 side a line drawn round the points of the basal star (fig. 20b), 

 but little of it is seen in a side view (fig. 20«), except where its 

 flanks are turned upwards above the rounded ends of the basals. 

 The articular faces are trapezoidal in shape, aud the pit in the 

 great dorsal fossa, which lodged the chief mass of the elastic liga- 

 ment,is unusually long and narrow, somewhat as in Ant. Oillerioni, 

 de Loriol. The transverse articular ridge above it is rather large, 

 and the opening of the central canal which pierces it much elon- 

 gated transversely, and also slightly constricted in the centre. 

 This indicates that the secondary basal canals, by the union of 

 which the axial canal of each ray is formed, did not in this 

 species converge quite so rapidly as in other Comatulce ; so that it 

 presents a slight approach to the condition found in Encrinus, in 

 which genus they do not unite in the first radial at all, but open 

 by two separate apertures on its distal face. The muscle-plates are 

 rather small, and separated by a wide but shallow notch ; they 

 are marked off from the ligament-fossae by faint cross ridges, which 

 run inwards from the sides, and then turn downwards towards the 

 rim of the opening of the axial canal, so as to leave a slight groove 

 between them (fig. 20 b). 



Diameter 9 millims. ; height 3 millims. 

 Locality. The Inferior Oolite, Cheltenham. 

 Remarks. This specimen was found by the Rev. P. E. Brodie, 

 M.A., F.Gr.S., who has kindly placed it in my hands for descrip- 

 tion. The relative width of the articular faces and the condition 

 of the muscle- and ligament-fossae indicate this tyj^e as an Acti- 

 nometra, though the articular faces are more sloping than in most 

 species of the genus. There are, however, one or two similarly 

 aberrant species in the ' Challenger' collection. 



