EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 223 



Kuckers shale (C2), Baron Toll's estate, near Jewe, and from Reval, 

 Esthonia. 



Plesioty'2)e.— Cat. No. 57302, U.S.N.M. 



British Museum, one thin section from the Kuckers shale, Baron 

 Toll's estate. 



STELLIPORA CONSTELLATA Dybowski. 

 Plate 4, figs. 9, 9a. 



StelUpora constellata Dybowski, Die Chaetetiden der Ostbaltisclien Silur-For- 

 mation, 1877, p. 48, pi. 3, figa. 9, 9a. 



I have not encountered this species in the collections studied and 

 must therefore Hmit my remarks to Dybowski' s description and fig- 

 ures. According to that author, the zoarium is lamellate and made 

 up of star-shaped clusters 6 to 8 mm. in diameter and 2 to 3 mm. dis- 

 tant from each other. Each star consists of 

 five to eight elongate, spindle-shaped, rhom- 

 boidal elevations arranged radially. The 

 clusters have no polygonal areas segregat- 

 ing them, but are arranged sometimes so 

 closely that the radii become confluent. 



Dybowski's illustration of the internal 

 structure is sufficient to show tliis species to 

 be a typical StelUpora and closely related to 

 the preceding S. revalensis. Indeed, it is 

 possible that they are identical species, the 

 main difference being the occurrence of thin 

 polygonal raised areas surrounding the 

 maculae in S. revalensis. As remarked be- 

 fore, this occurrence is not always constant in a species and the 

 type of S. constellata may have happened to be without them. 



Occurrence. — ^According to Dybowski, the species occurs in his 

 zone 2 at Hohenholm on the island of Dago. If in place, the specimen 

 would probably have come from the Lyckholm Hmestone (Fl) 



STELLIPORA APSENDESOIDES, new species. 

 Text fig. 124. 



Zoarium a single, incrusting, rounded cluster of zooecia and meso- 

 pores, 6.5 mm. in diameter and less than a milhmeter thick. Surface 

 exhibiting 12 radially arranged, sharply elevated, thin ridges bearing 

 small, subcircular zooecia, 0.13 mm. in diameter. Depressed areas 

 between the crests occupied by large, angular mesopores which are 

 closed at the surface in mature specimens. In thin sections the usual 

 characters of StelUpora, such as shown in S. revalensis, are indicated. 



Externally the zoarium has quite a resemblance to the Mesozoic 

 genus Apsendesia, as suggested in the specific name, but internally 

 the two are quite distinct. The fact that the growth consists of a 



Fig. 124.— STELLIPORA APSEIIDE- 

 SOIDES. A ZOARIUM, X3, AT- 

 TACHED TO A SPECIMEN OF ECHIN- 

 OSPHERITES. ECHTNOSPHEEITES 

 LIMESTONE (CI), REVAL, 



Esthonia. 



