86 LOWER PENINSULA. 



AULOPORA, GOLDFUSS. 



Colonies of prostrate, stout-walled tubes, attached with their 

 lower flattened side, multiplying by latero-basal gemmation. One 

 or two young tubes sprout from the lateral edges of the base of the 

 creeping tubes near the orifices, which then rise from the prostrate 

 into an erect position, while the new branches creep on, until they 

 again send off branches in the same manner, which latter, by coming 

 in contact in their spreading growth, adhere together and form retic- 

 ulated loops, or, if closely crowded, continuous laminar expansions. 

 Other species grow, by union of their tubes, into compact, thicker 

 masses. It; is rarely the case that they compose ramified branches. 

 The tubes nearly always exhibit a faint, longitudinal striation and 

 longitudinal rows of spinules encircling the inner cavity in more or 

 less rudimentary development. Remote, isolated diaphragms are 

 sometimes observed, but usually the tube cavities are open through- 

 out their entire length. Lateral pores connecting the contiguous 

 tubes channels do not seem to exist. The orifices project with 

 free circular margins ; occasionally, through being closely crowded, 

 the orifices of a limited spot may become polygonal from mutual 

 pressure. Certain minute Bryozoa, in manner of growth resembling 

 an Aulopora, have been confounded with this genus ; one of them 

 is Aulopora araclinoidca, Hall ; these have no affinity with Aulo- 

 pora, their structure being the same as in the Jurassic and cretaceous 

 genera Proboscina, Berenicea, or Stromatopora, whose utriculous 

 walls are perforated by numerous microscopical pores, comparable 

 to the minute punctations of the shell of a Terebratula. These 

 punctations can be distinctly seen in well-preserved specimens of 

 Aulopora arachnoidea, collected at Richmond, Indiana. 



AULOPORA SERPENS (?) Goldfuss. 



Prostrate expansions of conical tubules, one sprouting in a linear 

 row from the basal part of the orificial end of the other ; or at 

 ti mcs two of them fork off, and meeting others in the course of their 



