DESCEIPTIONS OF SPECIES. 117 



This description, although excellent, does not take into consideration 

 all of the characters of the species, nor some of its important variations. 



The mai'gins of the calices may be slightly elevated or very greatly 

 elevated. In some instances they may project as much as 2.5 mm., or in 

 extreme cases even 4 mm. The elevated jjortion of the corallites is subcylin- 

 drical. Costje are well developed in the region of the calicular margin, but 

 are low and rounded. The depth of the calice is variable; it is shallow 

 in low corallites, and deep in elevated corallites. The septa are usually thin, 

 but may be moderately strong. The margins are regularly and minutely 

 dentate. Near the inner termination of each of the principal septa, just 

 before it joins the columella, there is a distinct, moderately wide granulate 

 palus, or a strong jjaliform tooth. From the constant presence of these lobes, 

 I place the species in the genus Oculiuit. In Astrohelia palmata (Goldfuss) 

 from the Chesapeake Miocene, small lobes of quite similar character fre- 

 quently occur on the principal septa. Dissepiments are present, but are not 

 abundant. The size of the calices is necessai'ily variable; the usual size is, 

 as Milne-Edwards and Haime state, 4 mm. It varies from about 2.5 mm. 

 to 5 mm. 



Localities. — Vicksburg and Byrams Ferry, Mississippi. 



Geologic occurrence. — Vlcksbiu'g aud Rcd Bluff beds. 



Specimens. — United States National Museum (a magnificent suite) ; Wag- 

 ner Free Institute of Science; collection of T. H. Aldrich; Academ}- of 

 Natural Sciences of Philadelphia; Boston Society of Natural History; 

 Museum of Comparative Zoology, Cambridge, Massachusetts ; Mustjum 

 d'Histoire Natm-elle of Paris. 



The Mihie-Edwards and Haime types of A. lesueiiri are in Paris. 

 Conrad's types may be in Philadelphia, but I am not positive. 



Dr. William H. Dall possesses a series of four plates, engraved by 

 Lesueur, representing the fossils found at Vicksburg (Walnut Hills), Missis- 

 sippi. PI. I, fig. 14, represents a coral, most probably Oculina vickshurgensis 

 (Com-ad). 



The following not6s give a few details of the finer structure: The struc- 

 ture of this species and of Oculina diffusa, as nearly as could be made out, is 

 identical. The specimens are not sufficiently well preserved to permit the 

 character of the wall to be made out with certainty, but it seems to be the 

 so-called time theca. 



