REPORT ON THE TETRACTINELLIDA. 
cli 
coUenchymatous. The spicules are tetractinose, triactinose, and diactinose asters, and 
candelabra. 
Type — Placina monolopJia, F. E. Schulze (p. 278). 
Genus 2. Placortis, F. E. Schulze. 
Plakortis, F. E. Schulze, Zeitschr. f. wiss. Zool., Bd. xxxiv. p. 449, 1880. 
Incrusting Sponges, provided with an ectosome, which is traversed by a network of 
widely extending subdermal cavities. The chamber-system is aphodal, with wide short 
aphods. The choanosomal mesoderm is a granular collenchyma. The spicules are tri- 
and di-actinose asters ; candelabra are not present. 
Type — Placortis simplex, F. E. Schulze (p. 279). 
Family II. C o r t i c i d a:, Vosmaer. 
CoHicidai, Vosmaer, Bronn’s Klass. u. Ord. d. Thierreichs, Porifera, p. 324, 1886. 
„ SoUas {pars), Sci. Proc. Roy. Dubl. Soc., vol. v. p. 177, 1886. 
„ Sollas, Art. “Sponges,” Encyclopaedia Britannica, vol. xxii. p. 423, 1887. 
Microsclerophora with tetractinose asters and candelabra. The chamber-system is 
aphodal or diplodal. The mesoderm is in part sarcenchymatous, in part chondrenchy- 
matous. 
In my preliminary report I included the genus Thrombus in the Corticidse ; on 
account of the distinctive characters of its spicules it is now removed thence and made 
the t 5 rpe of a separate family. 
Genus 1. Corticium, 0. Schmidt. 
Corticium, 0. Schmidt, Spong. Adriat. Meeres, p. 42, 1862. 
„ F. E. Schulze, Zeitschr. f. wiss. Zool., Bd. xxxv. p. 410, 1881. 
The mesoderm of the ectosome and hypomere consists of chondrenchyme, which also 
forms the walls of the larger water-canals. The spicules are tetractinose asters and 
heterolophous candelabras. 
Type — Corticium candelabrum, 0. Schmidt (p. 280). 
Genus 2. Calcabrina, n. gen. 
Corticidae containing spinose microrabds in addition to tetractinose asters or 
candelabra. 
Type — Calcabrina plicata (0. Schmidt) (p. 281). 
