CHAEACTBRISTIC DEEP-SKA TVPES. 



SPOV 



IT.", 



beautiful specimens collected off Frederichstaed in 180 to _!< \8 

 fathoms, in thick globigerina ooze. A line Holtenia Pourta- 

 lesii (Figs. 531, 531 a, 531 b, 531 c) was collected by Pourtales 

 oft" Sand Key, in depths varying from 184: to 324 fathoms. 



The group of Lithistidae, as defined by Zittel, includes 

 sponges, formerly united with the Hexactinellidae, characterized 



Fig. 532. — Vetulina stalactites. Greatly magnified. (Schmidt.) 



by their connected calcareous spicules (Fig. 532 ), not built upon 

 the three-axis type, but forming an apparently irregular maze. 



The majority of the specimens of Vetulina stalactites (Fig. 

 533) are thick, undulating sheets, closely perforated with irreg- 



Fi»-. 533. — Vetulina stalactites. 4 



V 



ularly placed pores. The arrangement of the calcareous skele- 

 ton recalls to a certain extent that of the Hexactinellidae. The 



