344 PALAEONTOLOGY OF ILLINOIS. 



lined calcareous material. The vesicles generally decrease in 

 height outward, and, at least partially, already separated the 

 zocecia at their origin. True acanthopores and cystiphragms 

 never or only rarely occur, but certain peculiar spines of Li- 

 chenotrypa, cavernosa Nich, very much resemble the first. It also 

 appears that in the perfect state the zooecia apertures are cov- 

 ered by eccentrically perforated closures, and the perforation 

 itself seems at last to have been closed by a knob-like stopper. 



In all, ten Palaeozoic genera are included in this family, two 

 of them, Pinacotrypa Ulrich, and Botryllopora Nich., with 

 some doubt. As the student will perceive by referring to the 

 sub-joined synopsis of classification, each genus is distinguished 

 from the other by certain zooecial as well as zoarial peculiarities. 



A monographical study of the FISTULIPORID.E is very much 

 needed, and till the numerous and diverse forms of this exceed- 

 ingly difficult family have been subjected to a thorough investi- 

 gation, it will be utterly impossible to arrive at any satisfactory 

 conclusion with regard to the limits and really distinctive 

 peculiarities of the several generic groups now regarded as com- 

 prising the family. 



IV. CRYPTOSTOMATA:* In the typical section of this sub-order 

 the zoarium is bifoliate, consisting of two thin layers of zooecia 

 that have grown together back to back into ramose or foliar 

 expansions. In other groups the zoaria form fenestrated expan- 

 sions, consisting of only a single layer of cells, the reverse being 

 covered by a dense layer of striated or minutely granulose 



This suborder was proposed in 1883, by M. G. B. Vine, in his 4th report to the Brit. 

 ASFOC. on fossil Polyzoa. His Ptilodictya lonsdalei, which seems to belong to Phceno- 

 pora Hall, rather than to Ptilodictya of Lonsdale, is regarded as the type of the sub- 

 order, but his idea of the true relation and the extent of the proposed division must 

 have been vague, for he places here only the five geneia Ptilodictya, Arcanopora 

 (Cystodictya), Glauconome (Vine, non auct.), Stictoporella and Rhabdomeson, while the 

 FENESTELLED.E and ACANTHOCLADIID.S: and other allied Bryozoa are left with the Cyclosto- 

 mata. In "Notes of Joredale Polyzoa of North Lancashire," 1885, he increases the list 

 of genera to nine by the addition of Rhomlopora Meek, Hyphasmopora E. Ethridge 

 jun., Streblotrypa Ulrich, and Goniocladia E. Eth. jr. In my "Am. Pal. Bry.," I placed the 

 PTrLODicTYONiD-s; as th<i first family of the TEEPOSTOMATA, immediately following the 



FENESTELLID.33, ACANTHOCLADIID^ and ABTHROSTYLID.E (ARTHBONEMID.K) which W6r6 



arranged at the end of the CYCLOSTOMATA. Now, recognizing Mr. Vine's suborder, 

 those three families and the PTILODICTYONID.E and STICTOPORID.S;, as there arranged, 

 go to form the bulk of the CBYPTOSTOMATA as here understood. 



