256 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



two ranges of subimbricating [dorsal] plates, which are closely joined 

 along the median line; the marginal plates are the upper edges of the 

 adambulacral plates, which bear on their anterior ends one, two, or 

 three short spines." 



Formation and locality. From the Coeymans member of the Hel- 

 derbergian series of the Lower Devonic, at Jerusalem Hill, near 

 Litchfield, New York. The holotype is in the American Museum of 

 Natural History, No. 2302. There are two good specimens and a 

 single arm in the Beecher collection at Yale University. 



Genus SYMPTERURA Bather. 

 Text fig. 32. 



Sympterura BATHER, Geol. Mag., dec. 5, vol. 2, 1905, pp. 161-169, pi. 6, figs. 1, 

 2, 3, 6. SCHONDORF, Jahrb. nassauisch. Ver. Naturk., Wiesbaden, vol. 63, 

 1910, p. 216. 



Original diagnosis. "A Lapworthurid with spinulose disk ex- 

 tending to second arm segment, with oral skeleton of teeth, long 



A 3 



rame 



t&etk 



FIG. 32. SYMPTERURA MINVERI, AFTER BATHER. A. SEMIDIAGRAMMATIC RECONSTRUCTION OF SYN- 

 GNATHS, X 10. B. RECONSTRUCTION OF SEVENTH AND EIGHTH ARM SEGMENTS, x 18: a, DISTAL, AND ft, 



PROXIMAL PORTION OF VERTEBRA; C, 'ADAMBULACRALIAJ p, PODIAL DEPRESSION; q, INTERSPACE, OCCU- 

 PIED, AT LEAST IN PART, BY INTERVERTEBRAL MUSCLES. 



jaws, and short mouth frames (torus not seen), with free arm seg- 

 ments containing a vertebral ossicle, possibly compound, grooved 

 ventrally and provided on each side with two wings, to the distal of 

 which is attached an adambulacral spiniferous element." 



GenoJiolotype and only species. S. minveri Bather (same references 

 as above). The holotype was found in the Devonic (?Lower) at 

 Epphaven, near Padstow, North Cornwall, England. 



As this specimen presents in the ambulacralia characters of great 

 value in the morphology of the Ophiurid vertebrse, it is advisable 

 to quote here somewhat extensively from Bather's statements. 



"The median body of each segment is undoubtedly the equivalent 

 of the normal Ophiurid vertebra. On the accepted theory that 

 this -vertebra was evolved by the fusion of a pair of ossicles originally 

 alternating, then opposite, and finally joined along the middle or 



