BBACHIOPODA. 347 



Glossina.] 



We have two imperfect and exfoliated specimens which appear to be of this 

 species. Lingula covingtonensis Hall and Whitfield is sometimes regarded as iden- 

 tical with L. cobourgensis. An examination, however, will show that it is more 

 broadly oval and has sharply elevated, rather -distant, concentric lines. The striae 

 in L. cobourgensis are fine, elevated, sharp and closely crowded on the lateral slopes, 

 while medially there are fine concentric undulations with occasionally some radi- 

 ating lines. 



Formation and locality. Bare in the Trenton limestone at Minneapolis and Chatfleld, Minnesota; 

 Cobourg and Collingwood, Canada. 



Collectors. H. V. and N. H. Winchell. 

 Mus. Reg. Nos. 309, 3504. 



Sub-genus GLOSSINA, Phillips. 



1848. Glossina, PHILLIPS. Memoirs of the Geological Survey of Great Britain, vol. ii, pt. ii, p. 370. 

 1892. Glossina, HALL. Palaeontology of New York, vol. viii, pt. i, pp. 5, 6, 15. 



Species of this sub-genus differ from Lingula in having " an acuminate or sub- 

 triangular form, in which the rostral area is very narrow, with long, sloping post- 

 lateral margins, and a rounded or transverse anterior margin." (Hall, op. cit. p. 5.) 



This sub-genus is restricted to Palseozoic rocks. 



LINGULA (GLOSSINA) HUELBUTI JV. H. Winchell 



PLATE XXIX. FIGS. 13 and 14. 



1880. Lingula hurlbuti N. H. WINCHELL. Eighth Annual Report of the Geological and Natural 



History Survey of Minnesota, p. 62. 



Original description: ' Shell ovate, broadest in the anterior half, and pointed 

 posteriorly; the sides approaching the apex with a gentle convexity; lines tangent 

 to sides at one-third the length from the apex, form an angle of 72; anterior 

 angles obsolete. The exterior surface of the shell is marked by sharply elevated 

 concentric plications, which stand perpendicular to the shell, and on the anterior 

 third portion five occupy the space of one line, but towards the beak they are 

 reduced in size and increase in frequency so as to become mere striae. Where these 

 are largest and perfectly developed, the intervening grooves are destitute of ftne 

 striations. These plications leave corresponding lines on the interior cast when 

 the shell is exfoliated. There are no longitudinal radiations visible on the exterior, 

 but on the cast near the front are exceedingly dim, interrupted lines visible under 

 the lens, that possibly have the same origin, but these do not extend more than a 

 line and a half from the front margin, and they cannot be seen even with the lens 

 except under a favorable angle of reflected light. 



