COMMUNICATION PORES 357 



zooccial walls. These were seen by him in tangential sections only. The 

 sli-iiitiires mentioned by Ulrieh have since been seen and liuurcil in sev- 

 eral species of Homotrypa by. Ulrieh (28), Bassler (1). and Cumings 

 and Galloway (10). We also discovered and figured connecting foramina 

 or, as we prefer to call them, communication pores in Batosfoma (9) 

 and have recorded their presence in many other genera (9). Our re- 

 searches of the past few years have shown that communication pores are 

 present in abundance in many, in fact most, of the genera of the Tro])- 

 ostomata. They may be most satisfactorily studied in Hetero[ri//i(i. 

 Del'ayia, Peronopora, and Bythopo7-a. Figures 23 tq 30 will, we think, 

 convince any one that the appearances are actually due to pores passing 

 directly through the interzooecial walls. Figures 23 to 27 show the pores 

 as seen in tangential sections; figure 28 as seen in a longitudinal section, 

 and figures 29 and 30 as seen in longitadinal sections cutting trans- 

 versely to the direction of the pores. Figures 27 and 30 are from a 

 specimen of Heteropora iortilis, from the Miocene of Peter.sburg, Vir- 

 ginia, kindly sent us by Doctor Bassler. Except that the communication 

 pores of Heteropora are usually more flaring at the mouth (double fun- 

 nel-shaped), there is no discoverable difference between them and the 

 communication pores of the Trepostomata. The figures are drawn. with 

 absolute fidelity to the original sections. In ])oth cases the lamina of 

 the walls appear to be cut squarely off at the pores. This suggests the 

 possibility that the pores may have been formed by resorption. 



The appearance just mentioned caused us for a time to entertain the 

 possibility that the pores might- be perforations made by some sort of 

 parasite, possibly an alga or fungus. Perforation of calcareous tests by 

 such means is not an uncommon thing. Against this possibility, how- 

 ever, is the regularity and universality of occurrence of the communica- 

 tion pores, the fact that they pass straight through the walls, usually in 

 llic thinnest place. Ihcir iiiiir<niii diameter and ap])earanee, and, more 

 ihan anylhin.i;- else, ihc idcnlily of appcai'ance of the ]n>rr> in ihc Tre])- 

 osloniata and in 11 rlcrD/inni. It the hitter genus they arc ibdlnitcly 

 known 1(1 1)1' i-iiMiin iinicat imi |mm'cs. 



We have found these communication pores in greater or less abundance 

 and perfecti<tn in II cicrotrypa. J)fl-ai/!n. TTomotrypa, TTallopora, Am- 

 plexopora, Bylliopora. Eridolrypa. //omulrypella, Peronopora. Sfigiiia- 

 lella, BalofiloDia. Rliomholrii/ia. etcetera. It is likely that they were 

 universally ])rescnt in tlic Trepostomata. Similar structures have been 

 seen in Cceloclema, CeramoporeUa. etcetera; but the typical Heteropora- 

 like pore is developed only in the Trepostomata. 



