DESCRIPTIONS OF SPECIES. 161 



charakterlstischer Gattuugeu/ does not even mention the type species. So 

 although Pratz has added some interesting observations on the septal struc- 

 ture of some corals, he has not informed us what Thamnastrsea really is. 

 He has not given the name of the species on which he based his figures and 

 studies; therefore we do not know that he studied Thamnastrsea at all. 



According to Pratz's figure of Mesomorpha," the species under consid- 

 eration must belong to that genus, but it is impossible to decide whether it 

 is a Thamnastraja. The following is Pratz's definition of Mesomorpha:' 



Polypar massiv knollig, hiickrig oder astig. Zuweilen incrustirend. Kelche 

 niedrig, uiclit durch scharfe Grate umschiieben, sondeni durcli Septocostalradien 

 uutereiuauder verbunden. Eiiie Mauer feblt oder ist bocbtens rudimeiitiir und von 

 den Septacostalradien versteckt. Septa compact, an den Seiteufliicben luit Korncbeu 

 verseben. Die beuacbbarten Septalflacben sind durcb starke, ecbte Synaptlkehi mit 

 einander verbunden. Letztere verleiben dem zwiscben den Kelcbcentren beflndlicben 

 Sclerencbym bei unregebnassigem Verlaufe des Septocostalradien zuweilen ein 

 ccenencbym-artiges Ausseben. Der Septalrand ist regelmiissig gekornelt und deutet 

 auf einen trabecularen Aufbau bin. Siiulcbeu papillar, bauflg mit mebrereu Stern- 

 leisten verscbniolzen. 



There could be only one cause for questioning my generic reference; 

 this is, M. duncani has false synapticulse, but in my opinion, as already 

 expressed, whether synapticulfB are true or false is of no systematic value. 



Koby in discussing Thamnastra;a^ does not mention Thamnustnea den- 

 droidea, although the species occurs in the Jurassic of Switzerland. He 

 says (p. 557): "Je prends pour type des vdritables Thamnastrees la 

 Thamnastrcea amchnoides, dont je vais donner une description du polypier." 

 As the type of the genus has already been designatpd, Koby can not 

 change it. Until some one furnishes us a detailed study of Th. dendroidea 

 we are working absolutely in the dark on the relations of the whole set of 

 the so-called Thamnastrseoid genera. 



■ Ueber die verwandtschaftliolien Beziehungen einiger Korallen Gattungeu : Pah-eontographica, 



Vol. XXIX, 1882, pp. 92-98. ,. , ^-^.^- ,ooo 



"Eocane Korallen aus der libyscheu Wiiste und Aegypten: Pabi-ontograpliica, ^ ol. .\\X, 1S»<5, 



Pal. Theil, pp. 226-227, pi. xxv, figs. 45, 45a. 



^Eoc. Korall. aus der lib. AViiste, u. s. w. : Loc. cit. 



"Monogr. d. polypiers jurass. d. la Suisse : Mem. See. pal. Suisse, Vol. XVI, 1889, pp. 556-560. 



MON XXXIX 11 



