500 Leuckart: Bericht üb. d. wissenschaftlichen Leistungen 



Tubulär, unbranched, closed at the extremity. 



Euplectella cucumer. 



Lithistidae. Spicules developed upon a qnadriradiate divi- 

 sion of a central canal, held together by amorphous sarcode and an 

 interlocking of their filigreed arms, forming a reticulated glassy 

 structure, whose interspaces are more or less irregulär and curvi- 

 linear. Composed of two kinds of skeleton -spicules, those which 

 form a layer on the surface and are companied by minute or flesh- 

 spicules characterisiug the species, and those forming the body, which 

 are more or less alike in all the species and accompanied by fewer 

 flesh-spicules. 



a. Species in which the surface-spicule consists of a shaft and 

 three straight bifuroated arms all smooth and pointed. 



Dactylocalyx Bowerbankii, D. Masoni, Corallistes typus. 



b. The three sinuous arms branched. 

 Theonella, Dactylocalyx Prattii. 



c. The three sinuous arms compressed vertically; branched and 

 dentate or curvilinear on the margins. 



Mac-Andrewia, Corallistes clavatella, Kaliaspis. 



d. The surface-spicule consists of a short shaft and subcircular 

 discoid head, deeply and irregularly fissured. 



Corallistes polydiscus. 



e. The surface-spicule consists of a short shaft and subcircular 

 discoid head. 



Dactylocalyx polydiscus. 



f. The three arms of the surface - spicule sinuous, branched, 

 curvilinear, tubercled on the upper side or outer aspect, and fili- 

 greed at the extremities; shaft filigreed also at its extremity. 



Azorica Pfeifferae n. sp. Madeira. 



g. The surface-spicule is much the same, but with others like 

 those of Dactylocalyx Bowerbankii and D. polydiscus among the 

 body-spicules. 



Corallistes borealis n. sp. Faroe. 



h. The surface-spicule consists of a long shaft and three arms, 

 bifurcated and more or less tuberculated on the outer or upper aspect. 



Corallistes noli tangere. 



i. Surface-spicule like that of Dactylocalyx Masoni, with the 

 branches of the body-spicules in like manner glomerato-tubercled. 



Corallistes microtuberculatus. 



k. Surface spicule like that of Dactylocalyx Bowerbankii; the 

 rest with large filigreed head and long sinuous shaft filigreed at 

 the extremity. 



Corallistes elegantior. 



1. Species with curly filigreed spicules. 



