THE CYSTIDEA 



73 



Silurian, Indiana, may go here. Proteocystis, Barrande (1887), Lower 

 Devonian, Bohemia (Fig. XLL), differs from Sphaeronis mainly in the ir- 

 regular branching of the food-grooves, which stretch farther over the theca, 

 though whether the tegmen ever contained more than one cycle of plates 

 cannot be determined from the published figures. Apparently the hydro- 

 pore formed a slit between the small gonopore and the mouth ; and the 

 base, broader than in Spliaeronis, is said to have been prolonged into a stem. 



Flo. XL. 



Eucystis raripitnctata, oral surface! 

 after Angelin, enlarged. 



FIG. XLL 



Protencyst is Jlami, oral sur- 

 face, slightly restored from 

 JJarrande, enlarged. 



Fio. XI. 1 1. 



Mouth and food- 

 grooves of " Holn- 



after Miller' i& GUI - 

 ley. 



Its geological age forbids us to regard Proteocystis as a link bc-tween Sphae- 

 ronitidae and Glyptosphaeridae, but it certainly has points of likeness to 

 the latter family. Carpocystis, Oehlert (1887), Lower Devonian, W. France, 

 is a simple spheroid with large stem-attachment. Palmacystis, Haeckel 

 (1896), Archegocystis, & Codiacystis, Jaekel (1899), are forms with the 

 epithecal branched food-grooVes, described by Barrande as hydroplwrcs 

 palmees of Piracy stis, Craterina, & Aristocystis. 



FAMILY 2. GLYPTOSPHAERIDAE. Diploporita in which the food-grooves 

 extend over the theca well beyond the adoral circlet, and irregularly 

 transgress the sutures between the 

 thecal plates. Diplopores diffuse. 

 These represent a further advance 

 on the type of structure originated 

 in Sphaeronitidae. Genera 

 Glyptospkaera, J. Miiller (1854), 

 Orclovician, Baltic countries (Fig. 

 XLIIL), has for type the species 

 first figured by the Duke of 

 Leuchtenberg (1843), and dis- 

 tinguished by Volborth (1846) as 

 Sphaeronites Leuchtenbergi. The 

 spherical theca, reaching a diameter 

 of 7 cm., and larger than any other 

 cystid, is composed of irregularly 

 arranged polygonal plates, bearing 

 diplopores. The mouth is covered 

 by five orals (0) with characteristic bilateral symmetry, and from between 

 them the anterior unpaired, and lateral paired, grooves radiate about 



-. 



G - 



FIG. XLIIL 



Glyptosphaera Leuchtenbergi, after Volborth, nat. 

 size. For lettering, see adjoining text. 



