466 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
possible to show a different development of gullet-tube, and, in con- 
nection with it, a more or less complete separation of the so-called 
gastrovascular cavity ; thus leading the relation in the genera JEgir and 
Fenja to be regarded as the final stage of a process that has already 
begun in other Actinida. But certain knowledge in respect of those 
relations will scarcely be obtained except by investigations of embryons, 
as then it will be seen whether they develope themselves as genuine 
Coelenterata, or whether they possibly show themselves to belong to 
either Pseudocoelia or Enterocoelia. In the meantime I am satisfied 
with tlieir assignment to the great division Actinida, but have, however, 
found it necessary to form a new race (tribus) for them.” 
The family Sideractidse contains Actiniaria with numerous perfect 
septa ; there are a few series of short non-retractile tentacles, the inner- 
most of which contains eight mesodermal circular muscles ; Sideractis in 
some respects approaches Gosse’s genus Bolocera. Atlantactis has been 
placed with the Sagartiidm, though it does not possess acontia, which 
R. Hertwig, though not Andres and others, regards as distinctive of the 
family ; the same is true of Anthosadis. 
The Madionactidse are defined as Hexactiniae with few principal 
septa, acontia, and a prominent endodermal circular muscular system. 
Kodioides has a pyriform body, with a long bare stem which terminates 
in a pedal disc ; suckers are developed on the encrusted portion of the 
body. Gactosoma has a claviform body with an encrusted covering, the 
uppermost part being bare ; the surface of the body is furnished with 
suckers. The Andvakiidae are Hexactiniae, elongated, set loose in the 
sand, without any real pedal disc, and the greater part of the body 
encrusted ; the uppermost bare part of the body, the oral disc, and the 
tentacles are completely retractile ; the septa are few. Andvakia is, in 
many points, a transitional form ; in its internal structure it has several 
points in common with the Sagartiidae and Phelliidae, while in the external 
it differs considerably ; in these last it seems to approach Edwardsia , its 
body being divisible into three parts. 
The Mardoellidas are Zoanthidas which form colonies which, by 
means of a common rounded basal part, live freely in or upon the sand. 
Mardoel is allied to, and is perhaps identical with, a generic type charac- 
terized recently by Dr. Erdmann, but not named by him. 
Special notice must be taken of the beautiful plates which adorn as 
well as illustrate this important memoir. 
The Position of Sympodium coralloides.* — Prof. G. v. Koch de- 
scribes Sympodium coralloides Pallas as a genuine Alcyonid, which by 
adaptation to a special substratum (Gorgonid axes) has acquired an 
apparent approximation to the Cornulariidae. As an accurate compa- 
rison shows, it is really in close agreement and alliance with Alcyonium 
palmatum Pallas, and the author proposes to rename it Alcyonium 
coralloides. 
Marginal Sense-organs in Pelagiidae.f — Mr. R. P. Bigelow has a 
preliminary notice on this subject. He finds in the adult Pelagia 
cyanella a well-marked dorsal sensory groove, but no trace of the paired 
* Zool. Jakrb., v. (1890) pp. 76-92 (10 figs.), 
f John Hopkins Univ. Circ., ix. (1890) pp. 65-7. 
