SYNOPSIS OF GENERA. 



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Favosites, Lamarck (Cours. de Zool. du Mus. d'Hist. Nat. 1812). 



[Type, Favosites alveolata, Lam.] 

 Massive or branching Corals, composed of polygonal or circular cell tubes, 

 which are intersected by transverse diaphragms and connected by mural pores, 

 and in many species showing twelve longitudinal furrows. 

 Examples : Favosites Helderbergia, pis. iv, v and vi. 

 Favosites conicus, pi. iii, figs. 4, 6-13. 



Alveolites, Lamarck (Hist. Nat. An. Sans Vert. 1801). 

 [Type, Alveolites escharoides. Lam.] 



Corals massive, laminar or rarely branching ; composed of compressed cell 

 tubes, traversed by longitudinal furrows and intersected by diaphragms. Mural 

 pores large, usually situated near the angles of the tubes. Apertures with the 

 outer margin projecting. 



Example: Alveolites explanatus, pi. xiii, figs. 15, 16. 



Chaetetes, Fischer (Oryct. du Gouv. Moscou. 1837). 



[Type, Chaetetes radians, Fisch.] 

 Corallum growing in hemispheric or globular masses ; base covered with an 

 epitheca. Cells polygonal, contiguous, intersected by straight diaphragms, 

 without interstitial tissue or tubuli. 



With our pre.sent knowledge, it seems impossible to separate the forms 

 classed with Monotrypa from typical Ch^tetes. 

 Examples : Chmtetes colliculatics, pi. viii, figs. 1-4. 

 Chatetes monticulatus, pi. viii, figs. 5-7. 



Monotrypa, Nicholson (Pal. Tab. Cor., p. 320. 1879). 

 [Type, ChaBtetes undulatus, Nicholson.] 



Zoarium growing in irregular hemispherical or globular masses. Surface 

 smooth or with monticules of larger cells. Cell tubes contiguous, prismatic, 

 thin-walled and intersected by straight diaphragms. No interstitial cells or 

 spiniform tubuli. 



Example : Monotrypa ? spinulosa, pi. xvi, fig. 25. 



Monotrypella, Ulrich (Jour. Cin. Soc. Nat. Hist., vol. v. 1882). 

 [Type, Monotrypa agqualis, Ulrich.] 

 Zoarium ramose, smooth or tuberculated. Cells apparently of but one kind, 

 intersected by straight diaphragms. Walls thin, except in the peripheral 

 region. 



