126 WILLIAM BLAXLAND BENHAM. 
histology—and have to make some corrections in his descrip- 
tion, I feel justified in adding one more paper to the literature 
of the subject. 
I shall deal with the animal under the following heads: 
I. Anatomy. 
II. Description of species. 
III. Affinities of the genus. 
I. ANATOMY. 
Most of the following facts were obtained by a study of 
Ph. australis, Haswell, partly by means of dissection, though 
mainly by the study of longitudinal and transverse sections. 
In most cases the results were confirmed by comparison with 
similar sections of the Naples species. 
The spirit specimens which I received from Mr, Caldwell 
had been removed from the sac in which several of them live 
together, and which is now known to be formed by a species of 
Cereanthus; they had been killed with corrosive sublimate, 
and were very well suited to histological investigation. 
External Features.—The length of the individuals varies 
from three to six inches,” the diameter averaging about one 
eighth of an inch; but this diameter is not constant, as all the 
specimens showed swellings and constrictions at intervals along 
their length (fig. 1), as McIntosh has also observed in Ph. 
Buskii (19). At one extremity is the crown of tentacles, 
about half an inch or more across ; this extremity of the body 
I will call the “oral ” extremity, whilst the abtentacular end 
may be termed its “ aboral ” extremity. 
In all cases this latter extremity presented a slightly different 
appearance to the rest of the body. About a quarter of an 
1 The common Naples species is the one which Kowalevsky studied, and 
Mr. Caldwell has given it the specific name “ Kowalevskyi.” 
2 This species is thus considerably larger than Ph. Buskii, so that 
McIntosh must have seen only small specimens of the present species, as he 
states that his species of two inches is the longest known. 
