FAMILIES ATfD GEIfERA OP THE MADREPORARIA. 



135 



I. Alliance ASTR^OMORPHOIDA. 



Colonial Plesiofungidae. Calices small, more or less confluent by 

 costse. Walls absent. Septa trabeculate, but solid. Columella styli- 

 form. 



Genus Astr^omorpha, Reuss. 

 Genus Mesomorpha, Pratz. 



Genus Astr^omoepha, Reuss, " Beitrdge zur Char ok. d. Kreid. 

 in den Ostalpen,'' Denies, d. Kais. Ahad. Wiss. Wien, 1854, 

 Band vii. p. 127. 



Tlie colony is flat, with small irregular calices, having only 

 from 6 to 16 thick dissimilar irregular septo-costse only slightly 

 geniculate. The central septa unite with a compact styliform, 

 but sometimes rudimentary, columella. Septa not united directly 

 with the columella along their entire height, but by trabeculae 

 occurring at regular intervals from "5 to '75 millim. apart, so that 

 a series of openings exists on the boundary between septum and 

 axis. Tolerably stout, transverse or slightly oblique dissepiments 

 stretch across the interseptal loculi, agreeing with the axial tra- 

 beculse in number, but alternating with them. Hence a number 

 of superimposed cavities occur in the interseptal loculi. 



Eeuss notices the affinity of the genus to Clausastrcea, and how 

 it is distinguished from that genus and Thamnastrwa. 



E. Pratz (Palaeontographica, 1882, p. 103 et seq.) analyses the 

 species of this genus, and states that the genus is essentially 

 Triassic, the specimens studied by Eeuss from supposed Cre- 

 taceous rocks being derived fossils. The species described by 

 Milaschewitsch from Nattheim are Thamnastrseans, and differ in 

 their morphology from Astrceomorpha. The Eocene species is a 

 Thamnastrcea. 



E. Pratz remarks on the morphology. Tbe septa, instead of 

 being formed of many trabeculae passing from the internal base 

 of the corallite upwards and inwards, give the impression of being 

 formed by an independent irregularly-formed trabecule composed 

 of many nodules running upwards and outwards. The granula- 

 tions group themselves at tolerably regular intervals, and form 

 more or less horizontally placed enlargements, which run in the 

 same plane around each septum. In transverse sections, calca- 

 reous threads are seen to radiate from the middle of a septum to 

 the periphery. A vertical section shows that they are directed 

 upwards and outwards. The dissepiments resemble tabulaD, The 



