50 SIR C. WYYILLE THO-\ISON ON NEW LIV^ING 



111 Bathhi/criniis aldrichianus (fig. 1) tbe stem is, in full-grown 

 specimens, 200 to 250 millims. in length, and about 2 millims. in 

 diameter across tlie enlarged articulating end of a joint. The 

 longest stem-joints, from about the middle of the stem downwards, 

 have a length of 4 millims. ; and they rapidly shorten towards the 

 base of the cup. They are dicebox-shaped, and have their ends 

 bevelled off on different sides alternately, for the accommodation of 

 masses of muscle. Towards the base of the stem, a few strong 

 jointed branches come off and form a sort of imperfect root of 

 attachment. The cup consists of a series of basals which are 

 soldered together into a small ring, scarcely to be distinguished 

 from the upper stem-joint. Alternating with these are five large 

 triangular first radials : these are often free ; but in old examples 

 they also are frequently ankylosed into a funnel-shaped piece. 

 The second radials are articulated to the first by a true joint with 

 strong bands of contractile fibre ; they are broad and flat, with an 

 elevated vertical central Tidge which is continued down upon the 

 first radials (though in these it is not so marked), and lateral wing- 

 like extensions which curve up at the edges and are thus slightly 

 holloAved out vertically on each side of the central ridge. In the 

 third radials or "radial axillaries," which are joined to the second 

 by a syzygy, the upper border of the plate is nearly straight, but 

 it is divided into two facets for the articulation of the first two 

 brachials. The ridge is continued from the second radial to about 

 the middle of the third, where it divides into two, and its branches 

 pass to the insertions of the brachials to be continued along the 

 middle line of the arms. The wing-like lateral processes are con- 

 tinued along the sides of the radial axillaries and along each side 

 of at least the first three brachials. The arms are ten in number. 

 In the larger specimens they are about 30 millims. in length, and 

 consist of from forty to fifty joints. The first and second and the 

 fourth and fifth brachials are united by syzygies ; and after that 

 syzygies occur sparingly and at irregular intervals along the arms. 

 There are no pinnules on the six or seven proximal joints of the 

 ai^ms ; but towards the distal end there are usually about twenty 

 in two alternating rows ; the number and amount of development 

 of the pinnviles seems to depend greatly upon age, and not to be 

 verv constant. The arms and the pinnules are deeply grooved 

 within ; and along the edges of tbe'grooves are ranges of imbricated 

 reniform plates, fenestrate and very delicate, much resembling 

 those in the corresponding position in JRMzocrinus. The disk is 



