OPHIURA. lol 



Description. — The disc is siiiall imd wvy imicli distorted. The ventral 

 aspect of one arm is tlie only portion of the star-fish which affords much 

 opportunity for description. The ai-ni is al)out 18 mm. lonjf and 1- mm. broad, 

 and possesses the C3'lindrical characteristic shape of the genus. It is composed 

 of a h\rge number of square ossicles, which are superposed in the cross-section of 

 the arm, so far as it can be seen. They possess no spines, but a regular granula- 

 tion appears to run lineally across their breadth. 



Remarks. — This specimen is not sufficiently well ])reserved to ascribe it to a 

 definite species of the genus. 



Strafiijraphical Position. — Lower Chalk. 



CRETACb:OUS OPllIUROIDEA. 



Order— ZYGOVEI\J'RM, Bell (1892). 



Ophiuroidea, in which the movement of the ossicles on one another is limited 

 l)y the development of lateral processes and pits. Superior, inferior, and lateral 

 spine-bearing arm-plates are always present. The arms are simple and cannot 

 coil round straight rods. 



/<\,„i,7y_0l'HI0LEPIl)l D^. 



Zygophiura; with oral pa})illcB from three to six, of wliirli the last may bo 

 infradental. Arm incisures on the disc. Dental papilUe absent. 



Ge«((.s— OPHIURA, Lamard; 1801. 



Ophiuka, Lamarck. Histoire Naturcllo des Auimaux siius Vortobrcs, vol. ii. 



Ophiolepis, Mailer and Tranclul, 1842. System tier Asterideu (HraunscLwcij?). 

 Ophioglypha, Lyman, 1865. (OphiuridtD and Astrophytidtc) 111. Cat. Mus. Comp. 



Zool. Harvard, Nos. i, viii ; 1882, Kcp. Challenger Zool, 



vol. V. 

 Verrill, 1899. Keport on the Ophiuroidea collected by the Bahama 



Expedition in 1893 ; Iowa City, Bull. Labor. Nat. Hist., p. 1. 



Disc covered with plates or scales which are for the most part swollen. 

 Radial shields naked and swollen. Teeth. The inner niouth-papilhe long l)ut 



16 



