382 ART. 2.^H. MATSUMOTO : 



tory apparatus is very well developed more or less independently 

 in three lines, one of wliich is represented by the AmpJiiuridce and 

 Ophiotrichidce, the second by the Ophionereidinœ and Ophiocomîdœ, 

 and the third by Ophioceramis. As I have already explained, 

 OpMomusium is the most embryonal, i.e. paedomorphic form of 

 the OpMolepidince. 



In my opinion, the Ophiomastinœ present an almost unbroken 

 series of psedomorphism, of which the terminal members are such 

 genera as Astrophiura, Ophiophycis, Ophiomisldium, Ophiotypa, 

 Ophiomastus, Anthophiura, Aspidophmra, Ophlopyrgus, &c. The 

 grounds for this opinion have already been stated. If I am right, 

 the Ophiomastinœ, as well as Ophiomusium, must have been derived 

 from the other OpMolepidince by neoteny. 



The Ophioleucidce superficially resemble the Ophiodermatidœ, 

 but their true allies are, in my opinion, the Ophiolepidince. The 

 very thick and solid squamation under the superficial granules of 

 the disk, the usually internally joined radial shields, the rhomboidal 

 or lyre-shaped oral shields, the peculiarly long adorai shields, the 

 comparatively long oral plates, the articulation of the genital plate 

 and scale at their outer ends, the flattened arms, the very few — 

 usually only two — arm spines, &c. are characters usually observed 

 also in Opliiura and its allies. In certain genera of the Ophioleucidce, 

 the second oral tentacle pores show a tendency to be displaced 

 outside the oral slits. Ophiotrochus, which has partially soldered 

 oral papillae and very rudimentary dorsal and ventral arm plates, 

 may be the most embryonal, i.e. paedomorphic form of the present 

 family. 



It is theoretically to be expected that the very embryonal 

 forms of various families, e.g. Microphiura of the Ophi acanthi dee, 

 Astrophiura, Ophiophycis, Ophiomisidium, Ophiotypa, Ophiomastus, 



