262 THE ZOOLOGIST. 



terminal joint being a sharp claw. The third pair are often 

 eight to nine inches in length. The fifth pair are characteristic of 

 the class, and are simply small brush-like appendages. 



The abdominal segments of Lithodes maia are very re- 

 markable, and in the female sex differ from any other of our 

 known Crustacea. It will be observed by referring to Fig. 1, 

 that the plates on the abdomen of the male in this species are 

 quite symmetrical, being three on each side. Very different 

 however are those of the female, which are remarkably asym- 

 metrical, as shown in the sketch (Fig. 2.) 



It is difficult to account for this difference in the sexes, and 

 we cannot help thinking that this must be a species under- 

 going a change in form. Possibly, at some period of its existence, 

 it was akin in its habits to the Hermit Crabs, but for some 

 reason has discarded its ai'tificial protection, and may ultimately 

 become like true crabs (Brachyura) in having symmetrical plates 

 on the abdomen in each sex. It is difficult to imagine that the 

 process of change is in an opposite direction. 



The colour of this species is a pale dull red, varying slightly 

 according to the age of the specimen. 



We have been fortunate enough to obtain the zoaea form 

 of this somewhat rare crustacean, which is as curious in structure 

 as many other examples of this stage of development. It 

 resembles in appearance Neballa bijics, as figured on p. 130, vol. i., 

 of Mr. Gosse's ' Manual of Marine Zoology.' Its cephalo-thoracic 

 region is cylindrical, enlarging into a good-sized thorax ; the eyes 

 are large and sessile, and the legs are purely swimmers. The 

 abdominal segments are simple and graceful in form, terminating 

 in a remarkable filamentous tail. A comparison of this description 

 with that of the perfect animal just mentioned will show how 

 difficult it is to identify the unknown zosea forms of Crustacea, 

 unless they are attached to the swimmerets of the parent. 



Although this animal is not so much subject to the growth 

 of foreign substances upon its carapace as many other species, 

 yet it is occasionally encrusted with barnacles. 



We have obtained specimens of L. maia from the coast of 

 Northumberland, upon which were fine groups of Balanidse of 

 over an inch in height of the calcareous structure. Besides the 

 locality above mentioned, this species has been recorded by Bell 

 from the Mull of Galloway, Firth of Forth, coast of Ayrshire, 



