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the subdermal cavities. In the region of this lacunar system we 

 find calthrops , the rhabdome of which lies partly in the dermis. 



The parenchymal skeleton consists chiefly of oxeas placed in 

 bundies in three, directions vertically on each other. In addition 

 to the oxeas there are calthrops and asters. 



Spicules. Oxea. Stout or slender, straight or curved. 



Calthrops. Varying considerably in shape. Hardly two are 

 exactly like each other. 



Anatriaene. Very rare; perhaps of no specific value. 



Oxyaster. Not very frequent. Transitions to plesiasters and 

 spherasters. 



Microxéa. Extremely frequent. With high power very minute 

 spines or* knobs are visible. 



Found between Capri and Naples; 150 to 200 meter. 



Poecillastra cumana n. sp. 



The shape closely resembles the leaf of a water-lily, or what 

 in Botany is called obtusely cordate. The surface is rather smooth 

 on the touch. On one side of the very thin sponge numerous 

 procts are visible ; on the other side still more stomas. The size 

 is about 9X7X1 c.m. 



A transverse section through the leaf-like sponge shows a much 

 looser tissue than that of P. fragilis. Large lacunae are visible. 

 In fact the whole canal system is lacunar. The stomas commu- 

 nicate with subdermal cavities. The arrangement of the skeleton 

 is like that of P. fragilis. The presence of numerous asters in 

 the dermis distinguishes this species , among other characters , 

 from P. fragilis. 



Spicules. Oxea. Much more slender than those of P. fragilis. 



Calthrops. Varying in shape. 



Anatriaene. Very rare; perhaps of no specific value. 



Oxyaster. Very abundant. 



Microxéa. Generally smaller than those of P. fragilis; often 

 centrotylote. Found in the Bay of Cumae ; 150 meter. 



