BEVISED REPORT ON L.M.B.C. COPEPODA. 119 



from those figured by Clans chiefly in the form of the 

 prehensile posterior antennae and in the segmentation of 

 the abdomen ; but this animal appears to vary much in 

 these very particulars according to age and sex, and it is 

 therefore quite Hkely that Glaus' s specimens may repre- 

 sent slightly different stages of development. The group is 

 extremely interesting, as exhibiting progressive and retro- 

 gressive development, and deserves more attention than it 

 appears to have hitherto received. The female is about 

 l-18th inch in length, the male rather smaller, and the 

 larval form about half the size of the female. 



Since the above were recorded Prof. Herdman has found 

 a number of adult specimens of Lerncea hranchialis ad- 

 herent to the gills of whitings taken in the Eock Channel. 



Family Leen^opodid^. 

 AncJwreUa imcinata, Miiller. (PI. XXVII, fig. 2.) 

 Length (without ovaries) 2.20 mm. Several specimens 

 were found by Mr. Corbin on the gills of whiting taken in 

 the Mersey estuary. Microscopical examination of one 

 of them in situ shows the parasite impaled by the rounded 

 knob at end of arms to one of the clusters of gill rakers 

 which occurs at regular intervals along the concave side of 

 the branchial arches. These rakers serve to arrest the 

 passage of any solid substances into the gill cavities and 

 appear also to form a secure anchorage for parasites which 

 in Anchor ella are surrounded by a tough transparent 

 membrane. There are no males among those I have 

 examined. 



Explanation of Plates. 



Plate XV. 



Fig. 1. Calanus fiumcuxhicus, Gunner. a, Kostrum, 

 b, terminal spine of swimming feet. 



