ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 471 



central organ of the nervous system, whose existence was surmised on 

 physiological grounds by Eimer and Romanes. 



Memoir on Alcyonacea.* — Dr. W. May describes in systematic 

 fashion the Alcyonacea of the Hamburg and Berlin Museums, 67 species, 

 of which 38 are new : — 1 Clavulariidae, 8 Xeniidae, 5 Alcyonidae, and 

 21 Nephthyidae. Nine families are recognised : — Clavulariidae Hickson 

 (= Cornularidae M.-E.), Telestidae M.-E., Tubiporidae Gr., Xeniidae 

 Verrill, Organidae Dan., Alcyonidae Verrill, Nephthyidae Verrill, 

 Siphonogorgiidae Koll, Helioporidae Moseley. As the memoir is for the 

 most part taxonomic, it does not readily admit of summary, but it will be 

 of great value to those working at the Alcyonacea. 



Ancestry of Helioporidae.f — Prof. J. W. Gregory points out that 

 the blue coral Heliopora coerulea is one of the most isolated of living 

 animals ; it is the only known species of its genus (see infra), and it has 

 been recently described as the only member of its family. Some 

 Palaeozoic corals have a very similar structure ; but the view that these 

 extinct Heliolitids are allied to the Helioporids is strongly opposed by 

 some eminent palaeontologists. If these authorities be right, then 

 Heliopora is an animal with no close living relations and with no known 

 ancestors. 



The only fossil that has been regarded with any probability as a 

 possible link between Heliopora and the extinct Heliolitidae is the 

 Cretaceous coral Polytremacis, a genus founded in 1849 by d'Orbigny. 

 The author discusses the type species (P. blainvillei Mich, non Reuss), 

 and describes the structure. Thereafter, he discusses the relations of 

 Helioporidae and Heliolitidae. 



Polytremacis agrees with the Heliolitidae in many remarkable points 

 of structure, such as the presence of the aureole, the closure of dead 

 calicles by coenenchymal overgrowth, and the inconstancy of the septa 

 in the lower parts of the calicles. Polytremacis is allied to Heliopora by 

 equally striking points of resemblance, such as the fluted calicular walls, 

 with their numerous irregular septal ridges, the granular external sur- 

 face with its circumcalicular ring of septal teeth. On the axiom that 

 things that are allied to the same are allied to one another, the close 

 affinity of Heliopora and Heliolites seems more probable than some 

 palaeontologists are inclined to admit. Heliopora, in fact, may have 

 descended from the Heliolitidae by the reduction in size and consequent 

 increase in number and in variability of arrangement of the coenenchymal 

 caeca. 



In his systematic synopsis, Prof. Gregory adopts the following 

 arrangement : — 



Order Ccenotheculia, Bourne. 

 Fam. 1. Heliolitidae. 

 Fam. 2. Helioporidae. 



Genus 1. Heliopora. 



H. somaliensis sp. n. 

 H. edwardsi Stoliczka 

 H. boettgeri Fritsch. 

 Genus 2. Polytremacis, 5 sp. 

 Genus 3. Octotremacis g. n. 



* Jen. Zeitschr. Naturwiss., xxxiii. (1899) pp. 1-180 (5 pis.), 

 t Proc. Roy. Soc, lxvi. (1900) pp. 291-305 (1 pi.). 



