176 F. A. BATHER, CRINOIDEA OF GOTLAM). 



not belong to Herpetocrinus at all, but consisted of some arms of Streptocrimis crotalurus. '['lie 

 arms of the latter genus differ, as explained on pp. 124, 125, from those of all known crinoida 

 in the possession of 'false pinnules', structures, that is, which outwardly resemble pinnules, but 

 which differ from them in springing from the middle of the brachials instead of from their upper 

 corners, and in occurring in pairs instead of alternately. The brachials. in fart. are not axillary, and 

 the pinnules appear to have arisen as processes from the braehials rather than through the specialisa- 

 tion of originally dichotomous arms. These peculiar facts, inferred from the study of the type-specimen 

 of aS'. crotalurus, are fully confirmed by the fossils now under consideration ; and it will be remernbered 

 that it was this very peculiarity that justifiably preelnded me, in the absence of other evidenee, from 

 regarding them as the arms of a crinoid. It was, however, pointed out that these specimens had, in 

 other respects, a very arm-like character, and that they differed in certain important particulars from 

 other stems of the genus to which they were provisiojially referred. It only required the demonstra- 

 tion of a ventral groove with its covering-plates, now so beautifully accomplished by Mr. Liljevai.i. 

 (figs. 80, 81, 82), to prove that, despite their abuormality, they did really belong to the brachial 

 skeleton. It is no wonder that this fact was not discerned before, for the axial canal is exceedingly 

 minute, and is indeed not separated by stereom from the ventral groove, which is verv narrow and 

 very shallow (cfr. tig 195). 



The chief specimen consists of portions of tive arm-branches, all finials (figs. 78 — 80). Of 

 these, that on the left is independent (1), while the rest form two pairs (2, 3; 4, 5), each pair spring- 

 ing from an axillary (A; B). As the type-specimen of &\ crotalurus had certainly four and probablj 

 six or more branches to the ann, the present specimen may be a portion of a siugle arm; but it 

 may equally well be composed of portions of two or three arms, and it is in any case impossible to 

 say to which series the various brachials belong. The axillary A appears to be placed on the left 

 slope of another brachial, which also must have been an axillary and appears to have a portion of 

 another brachial attached to its right slope. These axillaries, surrounded as they were by matrix. are 

 what was before supposed to be a root. Similarly the brachials were described as columnals, and the 

 false pinnules as cirri. In other respects the previous description still holds good, and it is not 

 nccessary to repeat the measureinents. 



To the description of S. crotalurus it may now be added that the distal portions of the arms 

 did, as was suggested, bend upwards, and that they were, wheu closed, tightly coiled, like the arms 

 of Euspirocriiius spiralis and Gissocrinus mcurvatus, but not in the same plane. Y\ e also learn that 

 the false pinnules continued to the distal ends of the arms, usually arising on each side of a brachial. 

 but occasionally with some irregularity in this respect. In one case a false pinuule springs from the 

 suture between two brachials (fig. 79, third suture from *), each of which bears a false pinnule on 

 its other side. In other cases, as in branch 2 (fig. 80), the side of the brachial that does not bear 

 a false pinnule is shorter than the opposite pinnuliferous side, niuch as in an ordinary pinnulate 

 arm. The false pinnules possessed a ventral groove of broad V-shape, över which quadrangular 

 covering-plates, similar to those of the brachials, extended (fig. 82). 



P. 125, end of 1st paragraph, See above Note to p. 53. 



