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various species. Owing to the length of time which had elapsed since the Challenger collection 
was made, many of the specimens, preserved in strong spirit, did not satisfactorily show 
histological details: Also the small size of the polyps of most species made them difficult to 
handle: maceration was entirely impossible. Brook made sections through Antipathella sub- 
pmnata E. & S. (— Euantipathes subpinnataJ, Antipathella minor Br. (= Euantipathes minor'J, 
Antipathella contorta Br. (= Euantipathes contorta), Leiopathes glaberrima Esp. (= Euanti¬ 
pathes glabernma J, Parantipathes lamx (Esp.) Br., Cirripathes propinqua Br. ( = Eucirripathes 
anguina), Aphanipathes sarathamnoidcs Br., Pteropathes fragilis Br. (= Euantipathes fragilis), 
Tylopathes crzspa Br. (= Euantipathes crispa). Brook relieves the very rudimentary condition of 
the muscular system and the homogeneous mesogloea, which does not contain connective tissue 
cells, except in Cladopathes where the very thick mesogloea contains some stellate cells. Brook 
derives from his very extensive and precise descriptions, accompanied by very clear figures, the 
following points: the ectoderm has the same structure as in the Actinia, but the nematocysts 
are nearly’ always collected in batteries, as is the case with many Madreporia, but hardly ever 
with Actinia. These batteries are surrounded by hyaline or by very deeply staining glandcells. 
There is always a nervous layer, often provided with ganglia. There is always a muscular layer 
but with a very variable development; some species have mesogloeal dentations to which the 
muscular fibres are applied ( Leiopathes = pars Euantipathes and Cirripathes = Ezicirripathes'). 
The ciliated epithelial cells do not form so important a feature of the ectoderm as in Hexactiniae. 
The actinopharyngeal ectoderm is devoid of nematocysts, but there are found glandcells, a greater 
number of ciliated epithelial cells and frequently a muscular layer at its base, as is also the case 
in the body wall beneath the insertion of the tentacles. The mesogloea is always hyaline or 
subfibrous without isolated connective tissue cells as in Hexactiniae; Cladopathes has a relatively 
thick mesogloea with isolated stellate cells. The entoderm usually contains only the hyaline 
type of glandcells; the surface frequently consists of an irregular cubical epithelium. No nema¬ 
tocysts; the muscular system may be rudimentary or absent; always a nervous layer. — In most 
types the entodermal surface of the mesogloea is smooth, with a more or less important layer of 
musclefibres applied to it, first recognisable in vertical sections of the actinopharynx. Leiopathes 
(= pars Eztantipathes') and Cirripathes (= Eucirripathes') have their ectodermal and entodermal 
surface of the mesogloea dentate with a more or less convoluted layer of entodermal muscle- 
fibres. No musclefibres are found in the mesenteries, except in Cirripathes propinqua Br. (= 
Eztcirripathes anguina) where both sides of the primary mesenteries bear muscular fibres, but too 
rudimentary to admit of a decision being' taken on the direction of the fibres. Brook remarks 
that these facts indicate that the entodermal muscular fibres are of later origin than the ecto- 
dermal fibres. I he mesenterial filaments are found only along the free border of the primary 
transversal mesenteries; they bear a cap of ectodermal cells. The reproductive organs are 
developed in the primary transversal mesenteries only. They are of entodermal origin and are 
sometimes enclosed in a mesogloeal capsule. — Out of Brook’s anatomical descriptions I relieve 
the following points: the secondary mesenteries descend deepest on the actinopharyngeal side, 
while their connection with the bodywall ends on a much higher level. The actinopharyngeal 
ectoderm stains deeper than any other part, except the mesenterial filaments; at its surface 
