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this latter Isopod would appear, in some cases, at any rate, to 

 occupy the empty tubes of the sea-worm Sabella, and with its 

 peculiar tail protruding to imitate the head of the former tenant, 

 the male, which is exceedingly rare, is pelagic in habits and is no 

 doubt of a very inconstant disposition, roaming from place to place 

 and courting any lady of his own race whom he may come across. 

 His antennae are tremendously produced and are provided with 

 numerous sensory hairs, which doubtless assist him in discovering 

 brides. As opposed to such a frivolously disposed creature as 

 this, the male of Cyathura is. almost exactly similar to the female, 

 with which it lives in harmony in its muddy home. I have found 

 them in considerable numbers along the shore of Christchurch 

 Harbour, most frequently under stones and burrowing in the mud, 

 the tail being often exposed above the surface of the mud for 

 breathing purposes. Males and females are in almost equal 

 numbers, and I have had the young emerge from the brood-pouch 

 at the beginning of August. They are good swimmers, bending 

 their bodies and using their abdominal appendages as organs of 

 propulsion, but it is improbable that under normal conditions they 

 often leave the mud. As is the case with many Isopods it is very 

 difficult to discover upon what this species feed, but it is probable 

 that its food consists principally of organic particles contained in 

 the mud in which it lives : its mouth-parts are to some extent 

 modified for suction, but at the same time there is nothing what- 

 ever to incline one to believe that it is in any way parasitic in its 

 habits. Upon making dissections of the male I discovered a very 

 peculiar structure in the sexual stilet, which, as in most other 

 Isopods, is found attached to the inner branch of the second 

 abdominal appendage. This, instead of being a simple rod, as in 

 the case in all other Anthur'dae, and, in fact, wherever the stilet 

 occurs among the Isopoda, terminates in two large lobes, standing 

 out at somewhat of an angle to the main stem of the organ, from 

 one of which springs a slightly curved rod furnished at its ex- 

 tremity with a crown of large reflexed teeth. I have referred this 

 structure to the Rev. T. R. R. Stebbing, to Dr. Caiman, of the 

 British Museum, and to other authorities on Crustacea, but I can 

 hear of no analogous structure in any other Crustacean, nor have I 

 so far discovered the use of this strange sexual organ. It would seem 

 probable, however, that so marked a divergence from the usual 

 type is of considerable importance from an anatomical standpoint, 

 and I am hoping to work out the matter more fully before long. 

 It is somewhat remarkable that the anatomy of the male Cyathura 

 has never previously been examined in a proper manner. I may 

 mention that among other interesting features this is the only 

 member of the family which has the abdominal segments fused 

 together in the male. 



The other interesting Isopod which occurs in Chrstchurch 

 Harbour is Paragnathia Halidaii (Bate and Westwood), a small 

 and little-known species belonging to the important family 

 Anthur'dae. In the larval stage this species, like others belonging 



