A478 E. A. MINCHIN. 
yellowish granular mass without spicules, filling up the whole 
space which in Leucosolenia botryoides constitutes the 
ramified cavity. Then Gray made this sponge the type of a 
new genus, Clathrina, which he characterised by simply 
translating the original Latin diagnosis of Schmidt given 
above. 
Haeckel finds that Oscar Schmidt was in error in describ- 
ing the sponge as solid, and as the result of his studies he 
divides his Ascetta clathrus into four varieties. (1) As- 
cetta labyrinthus, with a single layer of endoderm-cells, 
and no endogastric septa or partitions. (2) A. meandrina, 
with the endoderm thickened to form a stratified epithelium 
of several cell layers, the uppermost bearing flagella. No en- 
dogastric septa or partitions. (3) A. clathrina, with the 
endoderm forming a stratified epithelium as in mzandrina, 
and the gastric cavity divided by partitions in which the em- 
bryos develop. (4) A. mirabilis, the colony consisting 
partly of A. labyrinthus and partly of A. clathrina. In 
A. labyrinthus alone did the spicules lie in a single layer ; 
in the other three varieties they formed several layers. 
The plexus of the anastomosing tubes was much looser and 
with wider meshes in A. clathrina than in A. labyrinthus 
and mzandrina, and the tubes themselves averaged a larger 
diameter (1—2 mm., sometimes 83—5 mm.) in the two latter 
varieties than in the former (where they measured 0:5 to 1 
mm., seldom more). In A. labyrinthus and meandrina 
the tubes were much twisted and contorted, reminding one of 
the gyri of the mammalian brain. In ail forms alike Haeckel 
found the colonies completely devoid of oscula, Auloplegma 
forms. He also at first thought he had seen oscula, but 
found he had mistaken artificial opeuings for such. Even the 
Olynthus forms were without openings, Clistolynthi. Since 
Haeckel’s monograph I know of no work dealing with the 
question of the lipostomy and variations of this interesting 
and beautiful sponge. Metschnikoff! describes the histology 
' “Spongiologische Studien IL: Anatomisches tiber Ascetta,” ‘ Zeitschr, 
f. wiss. Zool., xxx, 1878-9, pp. 358—s862. 
