Descriptioxs of Devoxiax Fossils. 229 



or composed of distinct concentric layers coating eacli otlicr. Large 

 pores, round or oval, about a fiftieth of an inch in diameter, Ijounded 

 (in perfect surfaces) by a sh'ghtly elevated border, and separated from 

 each other by a single row of smaller pores, of one-third to one-half 

 the diameter of the lai'ger pores, and more irregular in form. The 

 larger tubes, divided by transverse partitions, situated at distances 

 equal to two or three times the diameter of the tube ; the partitions in 

 the smaller tubes are much more closely arranged, there being three 

 or even four in a space equal to that occupied by one of the other. 

 Surface usually smooth, sometimes covered by low, rounded tubercles, 

 accompanied by a change in the form of the cell-aj^ertures ; but from 

 the occurrence of both these characters on the same specimen, they 

 can onl}' be considered as accidental features. 



Specimens not unfrequently occur with branches of Aulopora 

 imbedded in their substance, leaving only the aperture of the Aulo- 

 pora in sight, and the substance of the Fistulipora elevated around it 

 so as to present the appearance of a much larger pore, and in this 

 condition it might easily be mistaken for a distinct species. 



Formation and locality. In the marly beds, of the age of the 

 Chemung group, at Rockford, Iowa. 



Genus — ALVEOLITES Lamarck. 



Alveolites Kockfordensis n. sp. 



Coral lorming broad, irregular, discoid expansions, several inches in 



extent, and often an inch in thickness. Cell small, numbering in a 



section from forty to sixty in the space of one-tenth of an inch ; septa 



very thin and closely arranged, from two to two and a half in a space 



equal to the diameter of the cell-tube. Apertures very oblique, 



rhombic in outline ; the middle of the upper lip receding to a sharp 



elevated angle, and the center of the lower side occupying the groove 



formed by the junction of the two lower cells in advance. 



Formation and locality . In the marly beds, at Roekford and 

 Hackberry, Iowa. 



Genus — CLADOPORA Hall. 



The genus Cladopora, is described as consisting of ramose or reticu- 

 late branches, having tubular cells " radiating equally on all sides from 

 the apex, and opening upon the surfiice in rounded or subangular 

 expanded mouths; cells more or less closely arranged, but not always 

 contiguous, and apparently destitute of septa or rays." 



No mention is here made of communicating pores between the 

 different cell-tubes composing the mass ; nor are the original specimens 

 in a condition to show such a feature, except by careful manipulation. 

 It has, however, been seen in other forms, and the three ne\y species 

 here described show that such a feature does exist. Two of them 



