388 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to that of the immediate surroundings. The skin also reacts to light and 

 shade close at hand, and the tAvo sensory functions (of eyes and skin) 

 seem to interact. There is no evidence of image-forming or detection 

 of movements on the part of the eyes. The " eye " of Asterias is a 

 cushion at the base of the terminal tube-foot, and consists of numerous 

 minute pits. Each is an insinking of the epithelium, lined by pig- 

 mented rod-like sensory cells, surrounded by supporting cells, contain- 

 ing a watery transparent " emblem," closed in front by a lens, and over 

 that the cuticle. 



Study of Spatangids.*— D. A. Gandolfi Horyold finds ciliated epi- 

 thelium at the base at least of the spines which surround the madre- 

 poric plate, and a mucus secretion on the part of glands which lie 

 along the spines. It appears to be all-important that the madeporic 

 plate be kept clean from sand-particles and all debris, and if the tuft of 

 adjacent spines be removed then the Spatangid can no longer burrow. 



Coelentera. 



Structure of Sidisia.f — Fritz F. Livowsky has revised this genus of 

 sea-anemones, which is better known by the name Epizoa7ithus, and has 

 also given an account of the general and minute structure of the 

 polypes. The genus includes macrocneme Zoanthids, with a simple 

 sphincter-muscle lying in the mesogloea of the wall. The cavities or 

 diverticula of this muscle is only in a few cases in connexion with the 

 endoderm. The outer wall is always covered with incrustations ; the 

 ectoderm is usually continuous ; the mesogloea shows ectodermal canals 

 which sometimes coalesce in an annular sinus. The polyps are dioe- 

 cious. The coenenchyma usually covers the whole of the substratum, but 

 it maybe ribbon-like or quite reduced. Numerous species are described. 



Protozoa. 



Foraminifera as World-builders. J — Edward Heron-Allen and Arthur 

 Earland discuss the part that Foraminifera have played in forming 

 limestones and other rocks. There is no unquestionable evidence of 

 Pre-Cambrian Foraminifera, though Kirkpatrick maintains the Forami- 

 niferal character of Eozoon. Many relatively complex forms occur in 

 Cambrian strata ; there are many records of a few forms in the Silurian ; 

 the Devonian period presents but a single record ; in the Carboniferous 

 they begin to form enormous deposits ; the Permian and Permo- 

 Carboniferous rocks show a decline in the importance of Foraminifera ; 

 in the Trias and Jurassic they occur in many horizons, but do not 

 constitute any large proportion ; in the Cretaceous there were many 

 forms, but their number is as a rule small, compared with the whole bulk 

 of amorphous matter in the beds — the so-called " spheres " of the chalk 

 not being Foraminifera ; in the Tertiary times the Foraminifera had 



* R6sum6s des Communications, 9e Congres ZooL, 1913, pp. 20-1. 

 t Zool. Jahrb., xxxiv. (1913) pp. 557-614 (1 pi., 14 figs., and map). 

 t Journ. Quekett Micr. Club, xii. (1913) pp. 1-16 (8 pis.). 



