REVISION OF PALEOZOIC STELLEROIDEA, 79 



one of the five pairs constituting a part of the oral armature. In other 

 words, the adambulacral columns of adjoining rays are continued 

 around the axillary interbrachials by two modified plates. 



Ambulacral grooves deep, nearly closed by the adambulacralia. 

 Ambulacral plates not well shown but apparently carinate, one to 

 each adambulacral ossicle, and whether alternate or opposite can 

 not be stated. 



Locality and formation. — -In the middle and upper stages of the 

 Cincinnatic group (Ordovicic). The type-specimen (No. 1195, 

 Amer. Mus. Nat. Hist.) was found by Mr. D. H. Shaffer at Cincin- 

 nati, Ohio, probably in the Maysville formation, Mr. Vaupel found 

 a young individual showing the abactinal area (No. 60605, U.S.N. M.); 

 another young one was secured by Mr. Faber (No. 9568, University of 

 Chicago), and Mr. George Oeh found an excellent matured individual 

 preserving the actinal area (now in the Yale Museum), all from the 

 Maysville formation on the hills back of Cincinnati. Two good speci- 

 mens and another small poor one are in the Harris collection of the 

 United States National Museum (No. 59391) and were found in the 

 Waynesville division of the Richmond formation near Waynesville, 

 Ohio. 



A small astei-id preserving two rays and a portion of the disk is in 

 the United States National Museum collection (No. 23540) and was 

 found by Mr. W. P. Rust in the Utica shales one and a half miles east 

 of Rome, Oneida County, New York. It is associated ^vith Trinucleus 

 concentricus, Dalmanella testudinaria' multisecta, and other species. 

 The abactinal area only is shown, and appears to be that of Meso- 

 lialxaster shaffe/ri. It does not appear to be a Promo palseaster because 

 of the fewer columns of abactinal accessory plates, and tlie axillary 

 structure makes it almost certain that there is here but a single axil- 

 lary interbrachial plate. For the present it may be provisionally 

 referred to this species and attention is thus directed to it so that local 

 collectors may be on the lookout for other material. 



KemarJcs.- Tliis species has actinally much the appearance of 

 Hudsonaster incomptus, but the latter is at once distinguished by not 

 having the five axillary interbrachial plates of Mesa palseaster slmferi. 

 M. {?) parviusculus (Billings) is smaller, with far less plates in all the 

 columns than in M. shafferi. M. {?) parviusculus and M. granti differ 

 also abactinally and ambitally in the better developed accessory 

 plates. 



Cat. Nos. 60605, 59391, 23540, U.S.N.M. 



MESOPALiEASTER INTERMEDIUS, new species. 



Plate 9, fig. 4. 



This species is perplexing in its generic construction because of its 

 intermediate or transitional characters on the one hand (but least) 

 to Hudsonaster, and on the other (more decidedly) to Meso palseaster 



.'JOeOl''— Bull. 88—15 6 



