Jg4 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



do not touch except on outer lialf of ray but are joined by internal radiating ossicles 

 as in Mediaster, there being four to six radiating from each plate. The ossicles are 

 fairly large, except on outer part of ray. In the largo triangular meshes left by the 

 ossicles papula? emerge, but it is not possible to determine the number. On the side 

 of many of the tabula, usually obscured by the overhanging rim, is a curious pedi- 

 cellaria" with three to six slender curved jaws, about as long as the height of the 

 marginal granules. On the actinal surface, somewhat similar pedicellariae occur 

 on a few intermediate and adambuhii-ral plates near the mouth plates. These 

 have two, three, or four very slender, slightly tapering jaws. 



A highly important feature of the anatomy of Nectria is the presence of papulae 

 between the marginal plates. Near the base of the ray there appears to be more 

 than one to an area, but on the outer part there is only one. The series ceases at 

 about two-thirds the length of ray. 



The adambulacral armature and mouth plates are essentially goniasterid. In 

 the Victorian specimen there are three longitudinal series of robust truncate subpris- 

 matic or quadrate spinelets to each plate and about tliree in each series. The char- 

 acter of the armature is not unlike that of Mediaster and some species of Ceramaster. 



Superambulacral plates are present but not very well developed. They abut 

 against the lower end of the ambulacral ossicles and against a single row of spaced 

 supplementary internal intermediate plates, apparently distinct from the regular 

 actinal intermediate plates. Proximally some of the superambulacrals abut directly 

 against the actinal intermediates. 



Interbrachial septa made up of large flat imbricated plates. First ambulacral 

 ossicle enlarged. Tube feet with large sucking disks and double ampullae. .Actinal 

 intermediate plates imbricated internally, arranged in chevrons. 



Nectria agrees with typical Goniasteridae in the tabulate structure of the abac- 

 tinal ])lates, the form of the pedicellariae, and in the character of the adambulacral, 

 mouth, and actinal intermediate plates, but differs from the Goniasterinae in having 

 a tlefinite series of papulae between the two series of marginal plates. The genus 

 seems to be most nearh' allied to Mediaster, but on account of the presence of inter- 

 marginal papuliB is placed in a separate subfamily, the Nectriinae, Perrier 1894. 

 Perrier, however, failed to designate the really important character which distin- 

 guishes Nectria from other Goniasteridae. 



RosASTER. — I have examined Perrier's types in the Museum of Comparative 

 Zoology. Verrill places the genus near Paragonaster, but I think it is mucli nearer 

 Ni/mphaster, and well within Verrill's Mediasterinte. Perrier states that no pedi- 

 cellaria^ occur, but on the actinal surface of one of his types (No. 450, Coll. Mus. 

 Comp. Zool.) in two interradii there is a good-sized spatulate foraminate pedicellaria 

 whose expanded jaws reach nearly across the plate. A smaller specimen (R = 16 

 mm.) in the Stanford Collection (received from the ^Museum of Comparative Zoology) 

 also has two conspicuous ventral pedicellariae. Rudimentary superambulacral 

 plates (few in number and of very small size) are present. 



As compared with Nymphaster, the radial paxilliform plates are higher and more 

 spaced, and the interradial plates are slightly tabulate, not flat, as in Nymphaster. 

 Marginal plates of Rosaster have deep grooves between them, but no spinelets in the 



