462 _. MR. #, 'T, BROWNE ON [Mar. 17, 
Fam. BoUGAINVILLID&. 
PERIGONIMUS REPENS (Wright). 
Hydroid Form, 
Atractylis repens, Wright* (1858) ; Alder* (1862). 
Perigonimus repens, Hincks* (1868) ; Allman* (1872) ; Winther 
(1880); Duerdin (1893); Garstang* (1894). 
Perigonimus minutus, Allman* (1863) ; Hincks* (1868); Allman* 
(1872). 
Medusoid Form. 
Perigonimus repens, Crawford (1895). 
At Plymouth, on September. 2nd, 1893, I placed a colony of 
Perigonimus repens in a jar of sea-water. On the following day 
about a dozen meduse were budded off. On the 13th another two 
dozen were swimming in the jar from the same colony. None ot 
the medusze showed any signs of further development after their 
liberation from the hydroid colony. 
The umbrella of the medusa is about ¢ mm. in length and width. 
There are two opposite perradial tentacles and two opposite per- 
radial bulbs, without tentacles. Some of the specimens have a 
knob at the aboral end of the umbrella. The knob varies in size 
and shape in different individuals, in a few it is absent. 
Mr. W. Garstang sent me a colony from Plymouth, on March 
17th, 1894. On the 19th two meduse were budded off, one with 
a short knob at the aboral end of the umbrella, the other without 
a knob. Unfortunately 1 was not able to keep these meduse 
alive long enough to observe any further changes. Wright (1861) 
states that he has kept the medusa until it had four perradial 
tentacles and four interradial bulbs. 
_ Allman (1863) described another hydroid, Pertgonimus minutus, 
which, he states, is very much like Perigonimus repens. The chief 
difference is in the shape of the medusoid, which has a constriction 
across the aboral end of the umbrella. The figure given by 
Allman of this medusa agrees with the specimens with a conical 
knob, bred in my jars. Hincks (1868) has placed Perigonimus 
minutus as a synonym of Perigonimus repens; but Allman (1872) 
has again separated them into two distinct species. As I have 
obtained from the same colony meduse similar to Wright’s figures 
of Perigonimus repens and to Allman’s figures of Perigonimus 
minutus, I do not now see any reason for their separation into two 
distinct species. 
Distrisution, Denmark, Baltic Sea, Winther(H). Heligoland, 
Hartlaub (11). 
Scotland—Shetland Islands, Allman (H). St. Andrews, Craw- 
ford (M). Firth of Forth, Wright (H). 
England—Cullercoats (Northumberland), Alder (H). Plymouth, 
Garstang and E, T. B. (H). Ilfracombe, Hincks (H). 
Ireland—S.W. Coast, Duerdin (H), 
