PLATE CXV. 



Tubicolak Annelida of the Hudson River Group Cornulites ; in various 



stages of development. 



Pagtia 8 18. 



Fig. 1. A portion of the surface of a much macerated Orthoceras, showing tl artiest stages of growth 



observed; 

 Fig. 2. The same specimen, enlarged to three diameters, the relative distances between Hi" tubes being 

 diminished in the drawing. The tubes show every variation in form, from the completely en- 

 rolled helicoidal condition, suggestive of Spirorbis, to the partially enrolled or serpuloid stage, 

 and to theinore elongate, sinuous form characteristic of Cornulites. The Spirorbis dm iwnati 

 cn.iia. Miller and Dyer, probably represents the earliest or coiled condition of these bodies In 

 the smallest examples here illustrated the surface is entirely smooth, but with advancing 



growth becomes first faintly and then more strongly annulated. The largest of the speci ns 



also show faint longitudinal strias. In these latter tubes the embryonal tips have been broken off. 

 Hudson River group. Cincinnati. Ohio. 

 Fig. 8. Tubes in about the same condition of growth as those described in the preceding specimen, en- 

 larged to three diameters, showing the distinct transverse annulations. The tubes are all 

 attached for their entire length to a valve of Strepto rhynchus plano-convt tus. This is ths stage 

 of development represented by the species Ortonia minor, Nicholson. 

 Hudson River group. Cincinnati, Ohio. 

 Fig. 4. A. fragment of Monticulipora. bearing numerous tubes in the Serpuloid condition represented in 

 fig. '-!. Each of those tubes is finely but distinctly annulated, but the longitudinal stria' are but 

 partially developed. Enlarged to three diameters. 

 Hudson River group. Cincinnati, Ohio. 

 Fig. 5. A single, slightly Hexuous tube, natural size, with strong, somewhat irregular annulations and 

 very fine longitudinal strife. This is the condition of growth represented by the species 

 Tentaculites St< rlinr/i nsis of Meek and Worthen. 

 Hudson River group. Cincinnati, Ohio. 

 Fig. 6. The same stage of growth exhibited by three tubes attached to one another and, at their bases, to 



a fragment of a crinoidal stem. 

 Fig. 7. The same, enlarged to three diameters, showing the longitudinal stria'. 



Hudson River group. Cincinnati, Ohio. 

 Fig. 8. Three tubes of somewhat larger size and more flexuous form, attached to a crinoidal [fragment. 

 These specimens show an increasing irregularity in the annulations. 

 Hudson River group. Cincinnati, Ohio. 

 Fig. 9. An isolated group of similar tubes, attached to one another for their entire length and growing upon 



the fragment of a crinoidal column. ' Natural size. 

 Fig. 10. The opposite side of the same specimen. 



Hudson River group. Cincinnati. Ohio. 

 Fig. 11. A group of adnascent tubes attached to a valve of Strophomena atternata. 



Hudson River group. Cincinnati, Ohio. 

 Pig. 12. Two larger tubes attached to a single crinoidal segment. In this form the annulations have be- 

 come more, irregular and obsolescent, and the longitudinal stria? much more conspicuous. 

 Hudson River group. Cincinnati, Ohio. 



Fig. 13. Two adnascent tubes in which the annulations are extremely irregular, and have l> )me 



obsolescent. 



Hudson River group. Cincinnati, Ohio. 

 Fig. 14. A group of smaller tubes, showing the increasing irregularity and obsolescence of the annulations'. 



Hudson River group. Cincinnati, Ohio. 

 Fig. 15. A. large tube, having a surface of similar character to that represented in the last three figures. 



Enlarged to two diameters. 

 Fig. 16. A longitudinal section through the same specimen, showing the dense cellular wall and the folds 

 on the internal surface, corresponding to the external annulations. 

 Hudson River group. Cincinnati, Ohio. 

 Fig. 17. A group of simple tubes in a very early stage of development, having a common point of attach- 

 ment and a radiating habit of growth. 



Hudson River group. Cincinnati, Ohio. 



Fig. 18. The under or basal side of a sificified specimen, affording a more perfect illustration of this i ]o 



of growth. The outer walls of the tubes where shown are distinctly annulated. 

 Fig. 19. The upper surface of the same specimen, showing the apertures of the] connate tubes, the entire 



colony presenting a strikingly favositoid appearance. 

 Fig. 20. The view represented in fig. 8, enlarged to three diameters, 



Hudson River group. Cincinnati, Ohio. 

 Fig. 21. Basal view of a similar specimen, in a somewhat more advanced stage of growth, showing the 



point of attachment and the annulated surfaces of the tubes. 

 FiS. 22. The upper surface of the same specimen. 



Fig. 23. The same, enlarged to three diameters, showing the apertures and concentrically annulated inter- 

 nal surface of the tubes. 



Hudson River group. Cincinnati, Ohio. 



