VIII. (^ijitljiiivriinisi. 



211 



DRAWINGS TO ILLUSTRATE THE MORPHOLOGY OF 

 CYA THO CHIN U>S. 



1. 'I'he dissected cup; with the anterior radius on the right. 



2. Longitudinal median section through ten columuals of C. acinotuhus. 



s, stereora of ossicle ; m, matrix tilling axial canal ; c, calcita 

 taking the place of former ligament. 



3. Transverse section through the stem of C. acinotuhus. Lettering as 



above. Figs. 2 and 3 are both reduced from camera-drawiugs 

 of E 6004 B.M.; X o diam. 



4. Transverse section through a brachial (III Br) of C. acinotubus. Br, 



body of the ossicle ; u.r, axial canal ; vcj, ventral groove ; cp, 

 covering-plates. Reduced and restored from camera-drawings 

 of E 1367, B.M. ; x 8 diam. 



5. A young individual of C. acinotubus (?). The extreme length of some 



of the brachials may be only apparent and due to the difficulty 

 of seeing the sutures ; it is, however, noticeable in the young of 

 other genera. From an original drawing of M.P.G. vii |/^ ; nat. 

 size. 



o a. A first primibrach of the same, showing that the axial canal is not 

 yet separated from the ventral groove ; X 3 di.im. 



0. S'entral surface of tlie calyx of C. planus with ambulacrals and iuter- 

 ambulacrals removed. A, deltoids, and M, madreporite ; these 

 surround the peristome, and on their edges are seen indentations 

 for the reception of the ambulacrals ; x, anal. From E 6007, 

 B.M. ; X 2 diam. 



7. Veutral surface of the calyx of C. mammillaris, Phill., with tegmen 

 complete. A, deltoids, in great part covered by ia, interambu- 

 lacrals ; cp, covering-plates, which are irreju'lar ; .?•, anal, which 

 is partly broken, l^roni a drawing by ^Ir. Ilolliclc of E 268, 

 Ji.M. ; nat. size. 



