DESCRIPTIONS OF SPECIES. 



87 



At the calicular opeuliig- they are of equal size. Near the base 12 of the 

 costse are larger, the intermediate ones becoming- very insignificant; only 

 6 are prolonged to the basal tip. Intercostal furrows perforated by a double 

 row of pores. 



Septa moderately exsert, with entire margins, in three cycles, 24 in 

 number, their surfiices granulate. Columella strong, terminated above in a 

 hexagonal star, which projects slightly above the upper margins of the septa. 

 The septa of the first cycle fuse to the rays of the star. 



When a corallum of TurUmlia pharetra in cut longitudinally across the 

 septal planes, i. e., tangentially, it is seen that the septal surface is trans- 

 versely fluted (see PI. VI, fig. 10). When the flat surface of a septum is 

 examined, an extremely curious ornamentation meets the eye. Slopino- 

 downward from the wall, at an angle of about 45°, are regularly spaced, 

 parallel rows of granules. Near the base of the corallum there are two 

 granules iu each row; near the top four or five is the usual number. The 

 length of the rows is about half the distance between the wall and the colu- 

 mella. Along a middle vertical line on the side of the septum a series of 

 swellings on the septal surface begins. These are spaced similarly to the 

 rows of granules and are in a certain sense continuations of them. A row 

 of granules and a septal swelling together form a series. Where the o-ran- 

 ules cease the septal swelling begins, but the latter do not run in the same 

 direction as the former. They swing into a horizontal position and continue 

 tp the columella. The swellings are simply the septal undulations. (See 

 PI. VI, fig. 5.) 



In order to show the striking difi"erence between Turhinolia pliaretra 

 and TurUnolia sulcata Lamarck, with which it has been compared, a 

 longitudinal section of TurUnolia sulcata is represented on PI. VI, fio-. 4. 



Specimen No. 6 is the one from which PI. VI, fig. 9, was drawn. It 

 belongs to a variety quite abundant in the Lower Claiborne horizons of 



