10 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.76 



variations in the size, form, position, and direction of the genal 

 spines and in the size and form of the eyes and in the size of their 

 facettes, also modifications in the outline of the pygidium and in 

 the relative proportions of its lobes and segmentation may all be 

 immediately notable and serviceable pecularities in comparing species 

 whose cranidia are much less readily distinguishable. That there 

 is abundant room for yet other easily distinguishable intermediate 

 stages in the development of such parts appears when we compare 

 the genal spines and eyes of T. hicornis, T. mysticensis, T. hipuncta- 

 tus^ T. teUicoensis, T. iiiobergi^ T. hicuspis^ and other species of which 

 the free cheek is illustrated in this paper. That well-marked 

 specific differences occur also in the pygidia is sufficiently indicated 

 by comparison of these parts found with the cranidia of T. mys- 

 ticensis, T. fractus, T. hipunctatus, T. hicuspis, T . granulatus^ and 

 other species. In short, it is highly probable and also in conformity 

 with previous experience that if we had entire specimens even 

 closer specific discriminations would be warranted. Moreover, ex- 

 perience is showing more and more clearly that if we are to get 

 the utmost benefit from the fossils as stratigraphic and age indices 

 it is absolutely essential to discriminate the species as closely as 

 possible. 



DESCRIPTION OF SPECIES 



TELEPHUS FRACTUS Barrande 



Plate 1, Figures 3-7 



Telephus fractus Babeandb, 1852, Syst. Sil. du centre Boheme, vol. 1, 



p. 891, pi. 18, figs. 30-34. 

 Triloiites expectatus Bakbandb, 1872, Suppl. vol. 1, p. 146, pi. 2, fig. 10. 

 Telephus fractus (Barrande) Hadding, 1913, Slaktet Teleplius Barrande, 



Meddelanden Luuds Geolog. Ftiltklubb, No. 18, p. 38, pi. 2, figs. 20-22. 



(Discusses species and republishes copies of Barrande's figures.) 

 Not Telephus fractus of other Authors. 



Except Hadding's correction of previous views nothing has been 

 added to our knowledge of this species beyond the information given 

 by Barrande in 1852. Nor can I add anything except the statement 

 of my conviction that as yet the species is confined to Bohemian 

 localities. The Swedish form to which Angelin gave the name 

 T. wegelini and which Tornquist subsequently referred to T. fractus 

 was shown by Hadding to be distinct. Hadding also questioned 

 Heed's identification of Barrande's species in the Whitehouse group 

 of the Girvan District in Scotland, a doubt sufficiently warranted in 

 my opinion to induce me to propose the new name Telephus reedi 

 for the Girvan specimen. I agree with Hadding also in referring 

 to Telephus the free cheek figured and described by Barrande in the 

 supplement to his volume 1, under the name Trilohites expectatus^ 



