60 
Amplexus is usually associated with Zctphrentis in the Zaplirentoidea, 
but in the first instance I suggest that it he relegated to a family of its otvn 
— the Amplexkhe — with Pycnostylus , on account of their rudimentary septal 
lamella?, the very poor development of dissepimental tissue, even when 
present, and hy an inconstant fossula. This separation will then lead the 
way to the establishment of the Tryplasmidse, characterised hy the dentate 
or spinose free edges of the equally rudimentary peripheral lamella?, or the 
reduction of the latter to mere rows of granules, and the entire absence of a 
fossula and also dissepiments, with the possible exception referred to above. 
The reproduction in the first family is sexual, or asexual by calicinal budding ; 
in the second by parietal or calicinal budding, chiefly the latter, and mostly 
rejuvenescent. 
In proposing the separation of Amplexus from the Zaphrentida? I have, 
to some extent, been guided by the following remarks of Messrs. Thomson 
and Nicholson 1 : — “ Upon the whole, therefore, these two genera [. Amplexus 
and Zaphrentis ] are marked off from one another by characters of a more 
fundamental and recognisable nature than those which separate Zaphrentis 
from Cyathophyllum .” 
The interseptal loculi, if they can he so called, in Tryplasma are 
usually filled with stereoplasma, as in the Hadrophyllida?, but in that family 
there is a septal fossula, and the septal lamellae are entire, but dissepiments 
are not present. A fossula is also present in the Palaeocyclidae, but as to the 
existence of tabulae authorities differ, and as in the Tryplasmidae, the septal 
lamellae are rudimentary, and with crenulated free edges. Zittel and 
Nicholson refer to the absence of tabulae and dissepiments in the Palaeocyclidae, 
but Duncan describes both. 2 3 To separate Amplexus from the Zaphrentidae, 
and to place Tryplasma in a family of its own, seem to tend towards the 
simplification of a rather complex subject. 
Lindstrom, in 1882, s made use of the name Polyorophe for an Upper 
Silurian coral. This was described as a composite coral with obovate or 
elliptic corallites “ emitting frequent, large, broad hooks laterally, which 
connect adjoining polyparies the septa being represented by numerous 
lines of low, blunt spines. The tabulae are complete, spaced, and 
nearly horizontal, and the epitheca quite smooth. The only other author 
1 Thomson and Nicholson — Ann. Mag. Nat. Hist., 1S75, XVI (4), p. 424. 
* Duncan— Phil. Trans., CLVII, p. 651. 
3 Lindstrom— Bihang K. Sv. Vet.-Akad. Handl., 18S3, VIII, No, 9, p. 12. 
