16 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 76 



latter the anterior denticles are directed vertically downward, hence 

 they do not show in a dorsal view ; nor could they except the crani- 

 dium were so obliquely imbedded with respect to the bedding plane 

 of the matrix that in the compression of the latter the length of 

 cranidium — particularly the distance between the anterior margin of 

 the glabella and the posterior edge of the occipital ring — wouFd be 

 greatly reduced. Nothing like this is indicated by comparison of the 

 figures. On the contrary, the median thickness or width of the 

 occipital ring in Warburg's figures of the Leptaena limestone speci- 

 men instead of being less, as it should be, than in Hadding's figures 

 of supposedly typical specimens of T. wegelini is distinctly greater. 



In view of these probable facts I am convinced that the Leptaena 

 limestone specimen in question is not conspecific with T. wegelini 

 and therefore propose to distinguish and name it as above in honor 

 of the keen collector and observer who preceded me in recognizing 

 its specific entity. 



As I see it, the species that is as near as any to T. Unnarssoni 

 is the Bohemian genotype T. fractus Barrande. Warburg recognizes 

 this relation but regards them as distinct. However, in pointing out 

 the features in which they differ, that author mentions one that indi- 

 cates comparison of typical T. wegelini with T. fractus rather than 

 T. Unnarssoni. In the latter the front and sides of the glabella are 

 convexly curved throughout so that the sides even converge for a 

 considerable distance posteriorly. In fact posterior rounding of the 

 outline of the glabella is so unusual in species of the genus that it 

 struck me at once; and it is particularly notable in comparing 

 Warburg's figure of this cranidium with Hadding's figures of 

 T. wegelini. 



Warburg " having published a detailed description of the holo- 

 type of T. Unnarssoni under the name T. wegelini in English it 

 seems better to quote this than to attempt a description of my own : 



Cranidium about two thirds as long as wide. Axial furrows outside oc- 

 cipital ring very shallow, outside glabella deep and gently arched upwards, 

 at first slightly, but gradually getting more strongly convergent ; at the ante- 

 rior margin of glabella they bend nearly straight inwards and somewhat down- 

 wards, and are united by the short, nearly straight, and considerable narrower 

 preglabellar furrow. Glabella slightly more wide than long, oval, truncated 

 at base, rather swollen, highest joint in front of occipital furrow, posteriorly 

 slightly lieeled, front part somewhat overhanging. On the sides of the glabella 

 rather far forwards, there is a pair of very shallow, hardly discernible im- 

 pressions recalling the more distinct impressions in some other species of this 

 genus, as for example, T. Mohert/i Hadding," and T. americanus Billings." 

 Another slight impression is seen near the base of the glabella on one side, 



" Trilobites of the Leptaena limestone in Dalarnc, 1925, p. 90. 



"1913, Slaktet Telephus Barr, Geolog. Foren. Stockholm, vol. So, p. 37. 



i«Haddlng, idem, 1913, p. 37, pi. 2, figs. 12-17. 



