EXPLANATION OF PLATE XXI. 



DISCOSPARSA VARIANS Ulrich, p. 315 



1. An attached colony, (x2). 



2. A free colony, (x4). 



Vincentown limesand; Vincentown, (154). 



DIASTOPORA LINEATA Gabb and Horn, p. 316 



3-4. Views of two specimens, (x3). 



Vincentozvn limesand; Vincentown, (154). 



RETICULIPORA DICHOTOMA Gabb and Horn, p. 318 



5-9. Gabb and Horn's original figures. 



10. Transverse section of a fragment, (x6), (after Ulrich). 

 II-I2. Upper and lower portions of figure 10 enlarged 20 times 

 showing the tubes with a longitudinal direction in the 

 lower part; above they gradually turn upward while at 

 the top, fig. 11, they are nearly at right angles to the 

 length, (after Ulrich). 



13. Portion of one side of a fragment, (x2o), (after Ulrich). 



14. A broken gonicyst which was formed over a previous smaller 



cyst which remains intact, (x2o), (after Ulrich). 

 Vincentown limesand; Vincentown, (154). 



CRISINA STRIATOPORA Ulrich, p. 319 



15. The type specimen from the Miocene of Maryland, (x5^4)> 



(after Ulrich). 



16. Upper surface of one of the branches of the same specimen, 



(after Ulrich). 

 17. Lateral view of the same, (x23), (after Ulrich). 



18. Transverse section of one of the branches of the same, (xi7), 

 (after Ulrich). 



922 



