192 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
view of evolution by specialization on one of many characters all found in the 
primitive type. His remarks have such a close connection with the above 
interpretation, that I think it well to quote them somewhat fully. He says:— 
“... the primitive ancestors of the specialized groups are not distinguished 
from their modern representatives so much by simplicity of structure, but 
rather by combining in themselves the heterogeneous elements which have 
been segregated out in the course of evolution and separated into the different 
streams of descent that have given rise to the modern groups.” 
It was the habit of morphologists, and perhaps still is, “to imagine that a 
primitive ancestral form must have been simpler and have exhibited less com- 
The conclusions of this author form a very striking confirmation of the 
views of the evolution of the Heteroccela brought forward in this paper, and 
form an exceedingly strong argument on behalf of the position assigned to 
the Grantillidze herein. 
The above view of the evolution of the Heteroccela is shown below by means 
of a phylogenetic table :— 
Pharetronidee. Staurorrhaphide. 
\ Heteropidee. Amphoriscide. 
Chiphoride. \ a oA ' Grantidee. Sycettidee. 
| 
i) 
= wees 
eS 
| 
Ancestral 
Sycettide. 
The Amphoriscide are characterized by the presence of conspicuous sub- 
dermal quadriradiates, with their apical rays directed gastralwards. These 
quadriradiates have undoubtedly been produced by the addition of an apical 
ray to ordinary (regular or sagittal) tangentially placed dermal triradiates. 
It seems to me extremely doubtful whether the family is monophyletic in 
origin, and although I have not broken it up in the present instance, I am of 
the opinion that it will be found necessary to do so in the near future. 
