726 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Echinoderrna. 



New Order of Asteroids.* — H. Ludwig unites, under the title 

 iSTotomyota, a number of starfishes which have a peculiar musculature 

 on the dorsal surface of the arms. On the internal surface of the 

 dorsal integument there is a pair of longitudinal muscles, usually very 

 strong, which proceed not from the disk, but from the proximal region 

 of the back of the arms, beyond the disk. They extend to the tip, and 

 along with the ventral muscles serve to move the arm up and down. 

 Probably they make swimming movements possible. This should be 

 looked for in the North Atlantic Pontaster tenuispinus, which lives at 

 not very great depths. The new order includes two families : (1) 

 Cheirasteridse (with no unpaired marginal plates), including Pontaster, 

 Pectinaster, Luidiaster, Cheiraster, Marchast&r, and Gaussaster g.n. ; 

 and (2) Benthopectinida? (with an unpaired upper and lower marginal 

 plate), including Pararchaster and Bervbhopeclen. 



Incertae Sedis. 



Infection of Ophiuroid with Rhopalura.f — M. Caullery and 

 A. Lavallee placed large numbers of the ciliated larva? of Rhopalura 

 ophiocomse alongside of young specimens of Amphiura squamata in the 

 hope of discovering something in regard to the initial phases of infection. 

 To obtain the larvae it is only necessary to collect some Ophiuroids 

 in a vessel, for some of them are likely to liberate male and female forms 

 of Rhopalura through their genital clefts. The emissions almost always 

 occur about five o'clock in the afternoon. 



The larva? enter by the genital clefts. In a manner which remains 

 obscure, small plasmodia are formed, by the larva?, especially in the 

 vicinity of the gonads. These plasmodia are differentiated as male and 

 female, and form germ-cells, morula?, and embryos. 



Ccelentera. 



Reactions of Sea-anemones 4 — Georges Bohn has studied the 

 behaviour of sea-anemones at low tide in the winter or early spring. 

 When the tide goes out during the night, it often happens that the sea- 

 anemones do not close up at all. It seems that the closure at low water 

 is determined by an increase in the degree of illumination and not by 

 any mechanical, physical, or chemical change in the water. 



Madreporaria of the Gulf of Guinea.§ — Ch. Gravier describes from 

 San Thome and Prince Islands six species of Madreporaria, whose geo- 

 graphical distribution is very interesting. Four species are more or less 

 widespread in the West Indies, and occur also at the Bermudas, viz. 

 Mseandra cerebrum (Ellis and Solander), Favia fragum Esper, Orbicella 

 annularis Dana var., and Siderastrea radians (Pallas). One is found off 

 the Cape Verde islands, viz. Favia fragum Esper. Another, Oculina 

 arbascula Agassiz, is known as yet only from one other locality, namely, 



* SB. k. Preuss. Akad. Wiss., 1910, pp. 435-66. 

 t Coniptes Rendus, cl. (1910) pp. 1781-3. 

 X C.R. Soc. Biol. Paris, lxviii. (1910) pp. 964-6. 

 § Ann. Inst. Oc6anogr., i. fasc. 2, pp. 1-28 (9 pis.). 



