70 



BULLETIN 77, UNITED STATES NATIONAL MUSEUM. 



Measuring along one of these rows, four zooecia may be counted in a 



distance of 2 mm. 



Mitoclema horeale is distinguished from all other species of the genus 



by the shght projection of the apertures above the zooecial surface. 

 Externally the species has a great resemblance 

 to Diploclema trentonense Ulrich,^ with which I 

 had at first identified it, but thin sections 

 showed it to be distinct. A section across the 

 end of a branch failed to reveal the bifoliate 

 features characteristic of Diploclema, but 

 showed instead that the zooecia proceeded 

 from the center of the branches as in the type- 

 species of Mitoclema. 



Occurrence. — ^Abundant in the Wesenberg 

 limestone (E) at Wesenberg, Esthonia, where 

 the figured specimens were obtained. Less 



common in the Orthoceras limestone (B3) at Port Kunda (Cat. No. 



57186, U.S.N.M.) and in the Wassalem beds (D3) at Uxnorm, 



Esthonia (Cat. No. 57185, U.S.N.M.). 

 Cotypes.—Cai,t. No. 57184, U.S.N.M. 

 One specimen from Wesenberg is in the British Museum collections. 



Fig. 15.— Mitoclema boeeale . 

 Fragment of a zoaeium, 

 X9. Wesenbeeglimestone 

 (E), Wesenberg, Esthonia. 



MITOCLEMA ? MUNDULUM Ulrich. 



Text fig. 16. 



Mitoclema f mundulum Ulrich, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, 

 p. 177, figs. 4 a-c; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 

 123, pi. 2, figs. 4-6 



Fig. 16.— Mitoclema? mttndulxjm. oand 6, fragments, natural size, and X9; c, original of 6, XIS, 

 showing sueface character. Nematopoea bed of Trenton, Cannon Falls, Minnesota. (After 

 Ulrich.) d, portion of young example, X9. Kuckers shale (C2), Baron Toll's estate, near 

 Jewe, Esthonia. 



A single specimen from the Kuckers shale. Baron Toll's estate, has 

 all the characters of young specimens of Mitoclema f mundulum 



1 Geol. Surv. Illinois, vol. 8, 1890, p. 369, pi. 53, figs. 9-9c. 



