REPORT OH THE MYZOSTOMIDA. 
51 
The mouth (to.) and the cloaca (cl.) lie on a level with the ends of the parapodia ; the 
pharynx is well-developed, the intestinal caeca are much ramified. The male genital 
apertures are upon the summit of a broad obtuse elevation ($ ). 
(B) The form represented in fig. 3 was taken in the Caribbean Sea (“Blake” 
Expedition), and differs from A, especially by its dark brownish tint; the male genital papilla 
is extended into a tube, which is to be explained by the contractility of the structure, 
and does not therefore imply a specific distinction ; the same thing may be said 
concerning the differences in the length and thickness of the principal cirri and the 
arrangement of the secondary ones. 
(C) A third form (fig. 4) differs only from B by the smaller size of its body, and from 
A and B by the circular form of the suckers (?.), the regular intercalation of the secondary 
cirri, and the presence of two odd median cirri, one at either extremity of the body 
(C and C\). Nevertheless, bearing in mind what was said in the Introduction concerning 
the limitation of species, A, B, and C would appear to be identical. 
(D) Two specimens from Tortugas (“Bibb” Expedition), whose identity with the 
described forms A, B, and C must be considered as doubtful. One of them, represented 
in fig. 5, is ‘4 mm. long, and has twenty obtusely pointed cirri, arranged at equal 
distances from each other and of the same length ( , 07-'09 mm.) ; the odd median cirri 
are wanting. 
(E) Two individuals from Stations 45 and 249 of the “ Blake ” Expedition, as large as 
B, belong probably to this species, but they are too much damaged to decide the question. 
(F) Finally, there is a small specimen, found by Mr. P. H. Carpenter on a specimen of 
Actinometra meridionalis, A. Ag., sp., in the Copenhagen Museum. This specimen had a 
feebly developed cirrus behind, and is possibly an intermediate form between A and D. 
Also the body, which is ‘5 mm. long, is provided with abnormally large cirri. On the 
left side the first to the fifth, on the right the first to the eighth of the cirri are of equal 
length, about '09 mm., while the others are shorter, especially six to nine of them on the 
left side, which measure from ‘0087 mm. to ’02 mm. The tenth cirrus of the left and 
the ninth and tenth on the right are again a trifle larger, measuring about ‘03 mm. 
Hosts. — The only forms which can possibly be regarded as the hosts of this species 
are Actinometra meridionalis, A. Ag., sp., and Actinometra meridionalis, var. 
carinata, P. H. C. 
This may be stated with certainty for the forms 
(D) “Bibb,” January 1G, 1869, west of Tortugas. 
(E) “Blake,” No. 45, 1877-78. 
(F) Copenhagen Museum (U. S. Coast Survey, 100 fathoms). 
In all these three cases Actinometra meridionalis, A. Ag., sp., was the host. 
(E) This form was found upon both the mentioned forms of Actinometra, from 
Station 249 (Grenada) of the “ Blake ” Expedition. 
