398 On CalamoporcB in gravel deposits near Ann Arbor, Mich. 



The larger round tubes measure not quite two millimeters, the 

 smaller angular tubes one millimeter. Diaphragms of the smaller 

 tubes simple, straight, and somewhat distant, in the larger tubes 

 simple and compound or imperfect diaphragms are intermingled 

 as in Calamopora hemispherica. 



Pores arc large and numerous, surrounded bj a prominent 

 rim, placed in a single row on the sides of the smaller tubes; the 

 number of rows on the circumference of the larger tubes I could 

 not accurately ascertain. Also longitudinal sulci are noticed, 

 but in the specimens they are not plain enough to be counted. 



Cala7nopora hasaltica, Goldfuss Tab. 26, fig. 4. 



Occurs in tuberose or pyriform, glandular masses, with more 

 or less unequal polygonal tubes, from one to two millimeters 

 wide, ascending in a gentle curve, from the interior to the 

 outside. 



Diaphragms flat, simple, or more frequently compound, distant 

 about one millimeter. In parts of the surface, all the tube- 

 mouths are found closed up by opercula of a more substantial 

 and more regular construction than the ordinary diaphragms. 

 The latter are compounded of from five to eight linguiform 

 lamelhe, unequal in size and in level, so as to form by coa- 

 lescence an irregular angular surface; the opercula are formed 

 by 12 such lamellae, equal in size and in level, the sutures of 

 which give them a regular stelliform appearance. The centre 

 of the operculum is formed by a circular piece of concentrical 

 structure, and not by the coalesced acumina of the lamellae com- 

 posing the external ring. 



A similarly constructed operculum is described in Callopora 

 elegantula by Hall (Palasontology of New York, vol. ii, p. 144). 

 The opercula, as well as the ordinary diaphragms, can sometimes 

 be observed in the young state, in which the constituent lamellae 

 have not yet grown so far as to become contiguous, therefore iQ 

 the centre a corresponding stellate opening is seen. 



The compound diaphragms of this species are always in reg- 

 ular superposition, and do not exhibit the cellulose confused con- 

 dition which was described in Calamopora hemispherica. From 

 the side view they appear to be simple, and only rarely some 

 isolated lamellse are found protruding in the intervals between 



Pores form one, sometimes two, rows on each side. 



The adjoining tube-walls are separated at the surface by very 

 plam lines of demarcation which are sharply polygonal, wnue 

 the openings of the tubes often have a more rounded aspect 



