No. 4.] BILLINGS ON FOSSILS. 233^ 



inches in length, measured along all the curves. It is 15 liner 

 in diameter at 5 inches from the base, and about 18 lines at the 

 cup. The septal costae are very distinctly defined at the base 

 bui become more flattened and obscure upwards. In external 

 characters it resembles A. exilis, but the much greater derelope- 

 ment of the septa distinguishes it therefrom. 



To A. mirabilis, I add, provisionally, a specimen which whect: 

 perfect, must have been 2 feet in length. It is 17 lines in 

 diameter at the calice and about 11 lines at 12 inches below ' 

 There are about 45 large septa at the base of the cup, with an 

 equal number of smaller ones. Depth of the larger, 3 to 5 lines, 

 and of the smaller, 1 or 2 lines. As in the former specimen all 

 the septa are more or less curved. 



Both specimens occur in the Corniferous. 



Genus Zaphrentis. 



4. Z. INVENUSTA. — Corallum somewhat slender, expanding 

 to a diameter of 16 lines in a length of 7 inches. Surface with 

 numerous rounded rings of growth, of all sizes up to 3 lines in. 

 width. Costil striae about 8 in the width of 3 lines, where the 

 diameter is 10 or 12 lines. Where the diameter is 15 lines 

 there are about 50 large and the same number of small septa. 

 The larger have a depth of about 5 lines and the smaller 4 lines. 

 They seem all to be slightly flexuous at their inner edges. The 

 cup is about 1 inch in depth, the bottom smooth, flat or slightly 

 concave and 4 lines wide. There is a small septal fossette. 

 Occurs in the Corniferous. 



5. Z. Eriphyle. — Corallum turbinate, slightly curved, ex- 

 panding to a width of 2 inches in a length of about 4 inches. 

 Surface with numerous small, mostly sharp-edged rings of growth.. 

 Near the base there are 7 or 8 costal striae in the width of 3 

 lines; near the calice there appear to be 4 or 5. There are 

 about 60 large septa, at a diameter of 2 inches. Many of these 

 extend inwards to the centre. There are also 60 small septa, of 

 a depth of from 5 to 7 lines. Bottom of the cup nearly flat,, 

 about 10 lines wide. The septal fossette is of an ovate form, its 

 outer edge not reaching the margin, its inner extremity about 

 half way to the centre. 



This species is allied to Z. invenusta in having about the same 

 numbers of septa in the same width. It differs in having a. 

 much greater diameter, and the large septa reaching the centre^ 

 Occurs in the Corniferous. 



