276 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



branches given off in pairs from a median hypothetical arm, then we 

 must admit that the branching takes place within the test to an extent 

 otherwise unknown within the class. If we turn next to the structure 

 of the arms, we find no less striking peculiarities. No decisive 

 evidence exists to prove that vertebral ossicles are present, but if 

 they are they must be out of all proportion small compared with, the 

 lumen of the arm. Since the cavity of the arm is almost entirely 

 unoccupied by skeletal structures, the question naturally arises as 

 to the nature of the soft parts which it contained. The distal arms 

 are so large that they might well have afforded room for extensions 

 of the digestive viscera from the test. The absence of visible aper- 

 tures in the arms is another very puzzling feature, and one is almost 

 tempted to inquire whether the jjaired appendages are to be compared 

 with arms at all. 



"The nature of the buccal armature is very different from that 

 of any other Ophiuroid, though there is a certain amount of corre- 

 spondence in the paired structure of its five pieces. The absence of 

 any opening that could be taken for bursal apertures is noteworthy." 



Family EUCLADIID^ Gregory. 



Eucladiidse Gregory, Proc. Zool. Soc. London for 1896, 1897, p. 1040. — Sollas, 

 Quart. Journ. Geol. Soc. London, vol. 55, 1899, p. 692. — Sturtz, Verb, 

 naturh. Ver. preuss. Rheinl., etc., vol. 56, 1900, p. 204. — Schondorp, Jahrb, 

 nassauisch. Ver. Naturk., Wiesbaden, vol. 63, 1910, p. 236. 



Contains the genera: 

 Eucladia Woodward. 

 Euthemon Sollas. 



Genus EUCLADIA Woodward. 

 Plates 37, 38. 



Eucladia johnsoni a.. Woodward, GeoL Mag., vol. 6, 1869, p. 241, pi. 8. — Zittel, 

 Handb. Pal., vol. 1, 1879, p. 443. — SxtiRTZ, Verb, naturh. Ver. preusa. 

 Rheinl., etc., vol. 50, 1893, p. 30. — Gregory, Proc. Zool. Soc. London for 

 1896, 1897, p. 1040, fig. 6 on p. 1041.— Sollas, Quart. Journ. Geol. Soc. Lon- 

 don, vol. 55, 1899, p. 692. — Sturtz, Verb, naturb. Ver. preuss. Rbeinl., etc., 

 vol. 56, 1900, p. 183. — ScHONDORF, Jabrb. nassauiscb. Ver. Naturk., Wies- 

 baden, vol. 62, 1909, p. 47; vol. 63, 1910, p. 240.— Sollas and Sollas, Pbilos. 

 Trans. Roy. Soc. London, ser. B, vol. 202, 1912, pp. 214, 222.— Spencer, 

 Men. Brit. Pal. Asterozoa, pt. 1 (Palseontogr. Soc. for 1913), 1914, p. 50. 



This genus has seven pairs of arms in each radius, or 35 in all. 

 These are covered with finely scaly integument. 



GenoJiolotype. — E. johnsoni Woodward (citations as above). Lower 

 Ludlow formation, at Sedgley, near Dudley, England. Other species 

 are E. woodwardi Sollas, also from the Lower Ludlow, at Leintwar- 

 dine, England, and E. ? heecheri, new species, from the Lower Devonic 

 Coeymans limestone. New York. 



