Appendix to Part I. 179 



the branches were apparently very thin, but there is a relatively 

 considerable thickness of matter at the circumference. No traces 

 of transverse diaphragms have been noticed within the tubes. 



Cases illustrative of the changes to maturity and final oblitera- 

 tion in the Oval termination of the tubes are rare, but the following 

 have been observed. Where the mouth becomes free and oval, the 

 walls are thin and sharp, and perpendicular within the tube. In 

 some cases they are in contact ; but, in others, they are separated 

 by grooves of variable dimensions, in which very minute foramina 

 or pores may be detected. As the mouth approaches towards 

 maturity, the grooves are more or less filled up, and the walls 

 thicken, a row of very minute tubercles being discoverable along 

 the crest. At this stage the inner side of the tube ceases to be 

 vertical, being lined by a very narrow inclined band. The mature 

 mouths are separated by a bold ridge, generally simple, but not 

 unfrequently divided by a groove ; the double as well as the single 

 ridge being surmounted by a row of prominent tubercles almost 

 in contact with each other. Only one example of the rilling up 

 of the mouths has been observed, but it affords satisfactory evi- 

 dence of a gradual expansion of the inner band, before alluded to, 

 and a final meeting in the centre. In this extreme state, there is 

 a general blending of details, but the tubercles are for the most 

 part distinct. 



In this species, proofs of a narrowing of the mouth previously 

 to the formation of the perfect tube, and the final contraction, are 

 not very prominently exhibited in the long cylindrical straight 

 branches ; but near the point where the tubes bent outwards there 

 is an annular indentation, which may be traced successively from 

 cast to cast in a lineal direction, parallel to the surface ; and be- 

 tween the prominent narrowing and the perfect surface, the walls 

 of the tubes were slightly rugose. In another short branch, be- 

 lieved to belong to this species, but in which the tubes diverged 

 outwards very rapidly, the narrowing is strongly marked, but not 

 to an equal extent throughout the specimen. 



The matrix, in which the fossil is imbedded, is a coarse calca- 

 reous shale, or a gray limestone ; and in which occur also Fenestella 

 internata, &c. 



2. Stenopoea ovata, sp. n. 



branched, branches oval ; tubes relatively short, divergence great ; 

 mouths round; contractions or irregularities of growth nu- 

 merous. 



The characters of this species have been very imperfectly ascer- 

 tained. The branches are not uniformly oval, even in apparently 

 the same fragment. The tubes diverged rapidly along the line of 

 the major axis, and had but a very limited vertical growth. Their 

 casts exhibit a rapid succession of irregularities of development. 

 The mouths, as far as they can be determined, were round or 



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