5o NEW YORK STATE MUSEUM 



adambulacrals are able to close above the ambulacral grooves in the 

 distal portions of the rays, suggesting a tendency toward an envelop- 

 ment of the grooves. 



Encrinaster Haeckel 



The genus Encrinaster is represented in the Lower Devonian of 

 Germany by seven species and one variety ; a species from the 

 Caradoc of Great Britain has been referred here, but is con- 

 sidered as doubtful by Schuchert (op. cit., p. 245). In America, 

 E . p o n t i s , lately described by Doctor Clarke from the Lower 

 Devonian of Ponta Grossa and Jaguariahvva, Brazil, belongs here 

 properly, as also a species from the Silurian of the Argentine 

 Republic, also here described. The species described below as 

 E . p u s i 1 1 u s is from the Chemung beds. 



Encrinaster pusillus nov. 



Plate 17, figures 1 and 2 



The collections made by Mr Butts from the Chemung about 

 Elmira (Station O4, southeast of Elmira), contain a minute starfish 

 that exhibits characters widely distinguishing it from its asteroid 

 associates in the Chemung and Portage formations, and placing it, 

 in our view, in the genus Encrinaster, formerly Aspidosoma, so 

 well known from the Lower Devonian of Germany. The most 

 important of these characters are the petaloid form of the rays and 

 the structure of the actinal side of the rays. The rays are not so 

 broadly petaloid as in some of the typical species, but they com- 

 pare in that feature well with such species as Encrinaster 

 s c h m i d t i and the common E. tischbeinianus, and 

 they are sharply set off from the disk, thereby indicating that the 

 body cavity did not extend from the disk into the rays as in the 

 Asteroidea. The most important structure indicating that this 

 starfish belongs to the subclass Auluroidea, which are Paleozoic 

 brittle-stars, is reproduced in plate XVII, figure 2. It shows in 

 some rays the cast of the median canal from which short side 

 branches diverge that end in round nodes, the casts of depressions. 

 This structure is characteristic of the Auluroidea, as described by 

 Schondorf. 1 It consists of the median interskeletal water vessel, 



1 Friedrich Schondorf, Palaozoische Seesterne Deutschlands. II. Die 

 Aspidosomatiden des deutschen Unterdevon. Palaeontographica, v. 57, p. 37, 

 1910. See also Schuchert, Charles, Revision of Paleozoic Stelleroidea, with 

 special reference to North American Asteroidea. Smiths. Inst., Bui. 88, 

 p. 213. 1915, 



