BOMOLOCHUS ZEUGOPTERI. 41 



Antennules tolerably stout, shorter than the cephalo- 

 thorax and bearing numerous and moderately stout 

 plumose setas, first and second joints large, and, to- 

 gether, about as long as the combined length of the 

 next four, the third and fourth joints subequal, and 

 the penultimate joint shorter than any of the others.- 

 Second maxillipeds tolerably stout, the terminal claw 

 only slightly curved at the end, but at the base bent 

 backward upon the preceding joint. Thoracic legs 

 somewhat similar to those of Bomolochus onosi. Length 

 about 0*84 mm. 



JS'o males of this species have been observed. 



Habitat Found adhering to the back of a small 

 Midler's top-knot, Zeugoptems punctatus (BL), cap- 

 tured near the mouth of the Clyde estuary in Septem- 

 ber, 1897. About a dozen specimens, all females, and 

 most of tli em carrying ovisacs, were obtained ; they 

 were adhering firmly on the rough dark-coloured side 

 of the fish. 



This species is at once distinguished by the marked differ- 

 ence in the structure and armature of the second maxillipeds j 

 it is also a smaller species than the other two described 

 above. 



Genus 3. THERSITINA Norman, 1905.* 



Syii. Thersitcs Pagenstecher 1861, a name preoccupied by Pfeiffer 

 in 1855 for a genus of Mollusca, and by Spence Bate in 1857 for a 

 genus of Amphipoda. 



Ergasilides having the cephalic segment in the female 

 great ly enlarged and subglobular ; other thoracic and 

 abdominal segments small. 



Antennules short, stout, and composed of five joints. 

 Antennae also short, rather stout, and armed with a 

 tolerably strong, claw-like, terminal spine, from the 

 side of which springs a second and smaller one. 

 Mandibles, maxillae, and first maxillipeds somewhat 

 similar in structure to the same appendages in the 

 Lichomolgidae. Second maxillipeds small, two- or 



* ' Museum Normanianum,' III, Crustacea, second edition, p. 41. 



