476 Fossils of the Hamilton Group. 



Fig. IS. Avicula flahella is another of Vanuxem's fossils, be- 

 longing to the Hamilton rocks. 



The generic name is Latin, Avicula, a little bird ; specific name 

 flahella, a little fan. 



Fig, 14. Heliophyllum Halli^ (Edwards & Haime.) 

 Fig. 14. Heliophyllum Ilalli. This species was described in 

 the ISTew York Reports under the name of Cyothophyllum turhi- 

 natum, but in a splendid work lately published in France,* 

 wherein all the fossil corals then known of the palaeozoic rocks are 

 reviewed it is republished with the above new generic and specific 

 appellations. We translate the description of the learned authors. 

 " Coral turbinated or cylindro-conic, in general somewhat 

 lengthened and feebly carved at the base ; covered by an epitheca, 

 and presenting moderate concentric folds. Cup circular, mode- 

 rately deep ; one small septal fossette (a small cavity or furrow in 

 one side of the bottom of the cup) ; radiating lamellae very thin, 

 regular ; larger above, where they are rounded, denticulated on 

 their free sides, alternately a little inequal ; a little twisted towards 

 the centre ; they are 80 in number, or sometimes more. In a 

 vertical section it is seen that the lateral prolongations of the 

 lamellae are arched and ascending ; those which occupy the upper 

 part of the chambers terminate at the free sides of the lamellae ; 

 those which are situated lower unite in the centre to form irregu- 

 lar transverse septa ; these prolongations, which close incompletely 

 the interseptal spaces, are distant from each other a little more 

 than a millemetre, and are united by simple cross pieces at right 

 angles." 



The generic name is from the Greek Helios, the sun, and 

 phyllon, a plant. The specific name was given in honor of Pro- 

 fessor Hall. 



* Polyjjiers fossiles des terrains pal ceozoiques (Fossil corals of the palceo- 

 zoic formations,) par M. Edwards et J. Haime. 



