8 



L., with a stray specimen or so of Clytia johnstoni, Alder) and 

 red seaweed growing on the carapaces of several individuals 

 of Hyas araneus, brought from Redcar, August 4th, 1883. The 

 specimens observed were of various ages and stages of 

 development, but all very young, the size of the largest being 

 about i-i6th inch, and the smallest not more than half that. 

 The most fully-developed form noticed had five pairs of 

 branchial appendages, the second pair well developed, the 

 fourth pair also well developed, but a little smaller than the 

 second ; fifth pair somewhat small; first pair very small; and 

 third pair between first and fifth in size. (The numbers of 

 the pairs in remarks on earlier stages are taken from this stage.) 

 Younger specimens had first pair very small, fifth pair small, 

 and third pair merely tubercles. Still younger form had both 

 first and third pair of branchial appendages merely tubercles. 

 In the youngest form observed the fifth pair also were little 

 more than tubercles. These pairs of appendages would seem, 

 therefore to develop in the following order ; — second, fourth, 

 fifth, first, third. The members of each pair are opposite or 

 nearly so, and one of them seems often to develop in advance 

 of the other, and remain the larger for some time. In the 

 typical E. exigua there are two rows of tentacles on each side 

 of the dorsal line, but I think there can be little doubt that in 

 my specimens the second row is absent merely on account of 

 age, particularly as Alder, in his description, gives "set of five 

 rows of one or two each," presumably meaning on each side, 

 so that the outer row does not appear to be constant, and is 

 always less fully developed than the inner one. The only 

 other species which my specimens might probably belong to 

 is E. despecta, A. and H., but this has only eight appendages, 

 and they are markedly alternate — while the dorsal line is 

 waved. The Redcar specimens agree with E. exigua in the 

 banding of the branchial processes, though some of the 

 youngest scarcely show it, and are more like E. despecta. The 

 tentacles also agree with E. exigua, and are quite unlike those 

 of E. despecta. 



This species has been recorded from the Northumberland 

 coast, and is usually found on Laminaria and Fuci in shallow 

 water, especially on those fronds that bear Obelia geniculata. 



