HATSCHEKIA MULLI. 115 



to those of Hatschekia hippoglossi. Thoracic legs two 

 pairs, each composed of a stout two-jointed basal part, 

 which is furnished with two short two-jointed ranii. 

 Egg-strings long and slender. Length of adult female 

 exclusive of egg-strings 3 '4 mm., and including egg- 

 strings about 10 mm. 



No males have been observed. 



Habitat. Parasitic on the gills of red mullet, Mullus 

 barbatus. Recorded from Plymouth by Dr. Bassett- 

 Smith. Observed also on the gills of four specimens 

 of red mullet sent to us from Looe, Cornwall, by 

 Mr. N. M. Richards of that town, and on one from 

 Plymouth sent by Dr. E. J. Allen, Director of the 

 Plymouth Laboratory. It was also on Mullus barbatus 

 that Professor van Beneden obtained his specimens of 

 HatscheJda mulli. 



A feature which appears to be peculiar to this species, and 

 which was also noticed by van Beneden, is the secondary 

 process at the base of each antenna : this process diifers from 

 that of any of the other species known to us. 



H. mulli is readily distinguished from other members of 

 the genus recorded here by the dorsal humps on the thoracic 

 region, and the small lateral lobes at the posterior end. A 

 young female is represented in dorsal view at fig. 3, and it 

 also shows traces of the characters by which the species is 

 distinguished. 



3. Hatschekia labracis (P. J. van Beneden). 

 (Plate XXXIII, fig. 2 ; Plate XXXIV, figs. 6, 7.) 



1870. Clavella labracis P. J. van Beneden. (16) pp. 45 & 46, pi. i, fig. 4. 



1901. Clavella labracis T. Scott. (113) p. 127. 



1902. Clavella labracis T. Scott. (114) p. 292, pi. xiii, figs. 10-12. 

 1904. Clavella labracis A. Scott. (109) p. 40. 



Female. Cephalothoracic, segment, seen from the 

 dorsal aspect, rhomboid or diamond-shaped, the lateral 

 margins produced so as to form distinct angular pro- 

 jections ; the width of the segment across the lateral 

 angles rather greater than the length and equal to 

 about a fifth of the entire length of the animal. Genital 

 segment elongate-ovate, about three times as long as 

 the cephalothorax, widest in the middle and with the 



