NOTES ON A SPECIES OF BARNACLE. 
405 
COMPARISON WITH OTHER SPECIES OF DICIIELASPIS. 
Darwin (1851-54) gives five species under this genus, and says of their dis- 
tribution : 
Eastern and western warmer oceans in the Northern Hemisphere, attached to Crustacea, sea- 
snakes, etc.; attached to crabs at Madeira and off Borneo; to sea-snakes in the Indian Ocean. The 
individuals of all the species appear to be rare. 
Since Darwin four species have been added to the genus: I). darwinii de Filippi 
(’61 and ’61a), very abundant on the gills of Palinurus vulgaris in the Mediterranean; 
D. neptuni (MacDonald) Hoek (MacD. ’69 and Hoek ’83), on the gills and respiratory 
appendages of “ Neptunus pelagicus, one of the swimming crabs occurring in great 
plenty at Moreton Bay, Australia”;* I). aymonini Lessona and Tapparone-Canefri 
(’74), found on the gills of Machrochira haemferi sent from Japan by Cav. Aymonin, 
then living at Yokohama; finally, I). sessilis Hoek (’83), collected by the Challenge r 
expedition in the Atlantic near the Azores, attached to a spine of an Echinid from 
1,000 fathoms. 
I reproduce in part a table for the identification of species, given by Dr. P. P. C. 
Hoek (’83, p. 48): 
1. Carina terminating in a disk D. warwickii , D. grayii, D. peUucida 
2. Carina terminating in a fork D. neptuni, D. aymonini, I). darwinii, D. lowei 
3. Carina terminating in a cup D. orthogonia, D. sessilis 
(2) is further subdivided: 
I. Basal segment of scutum directed toward centrum of capitulum D. neptuni 
II. Basal segment of scutum parallel to lower margin of capitulum. 
(a) Capitulum almost as long as broad [intended for almost as broad as long?]. 
a. Tergum triangular D. aymonini 
(3. Tergum divided by a deep notch D. darwinii 
( b ) Capitulum more than R- times as long as broad D. lowei 
Thus the form of the carina, the direction of the basal segment of the scutum, 
and the shape of the tergum, with other points of difference, exclude this barnacle from 
* MacDonald describes this form as somewhat between Lepas and Dichelaspis and gives it the name Paradolepas 
neptuni; but Hoek refers it to the genus Dichelaspis. 
