LERN/EENICUS SPEATT^J. 157 



1900. Lernseenicus sprattx T. Scott. (112) p. 161, pi. vii, figs. 7-10. 

 1907. Lernn'cnicug sprattse A. Scott. (Ill) p. 94, pi. ii, figs. 1-5. 



Female. — Body elongated, slender; head somewhat 

 enlarged, and provided with two stiff horn-like pro- 

 cesses, one on each side and extending obliquely back- 

 wards. Thorax, between the head and the genital 

 segment, slender and neck -like, with a number of 

 minute constrictions, giving to this part of the body a 

 moniliform appearance ; genital segment moderately 

 elongated and increasing somewhat in thickness pos- 

 teriorly. Abdomen rudimentary and not very clearly 

 defined, apparently destitute of appendages. 



Antennules short, distinct, setiferous, indistinctly 

 two- jointed, the end joint being shorter than the 

 other ; antenna? very short, stout, strongly chelate 

 as in Pennella; other mouth-organs somewhat rudi- 

 mentary. Thoracic legs small, situated immediately 

 posterior to the head ; first and second pairs biramose, 

 rami two-jointed ; the next two pairs uniramose, the 

 rami being also two-jointed. In fresh or living speci- 

 mens the colour of the genito- abdominal segment is 

 greenish. Egg-strings long and slender, usually 

 exceeding the length of the body, which, exclusive of 

 the egg-strings, measures about 18 mm. 



Habitat. — Usually found parasitic on the eyes of 

 sprats, Olupea spratta, and sometimes also on other 

 parts of the body. Occasionally more than one para- 

 site will be found adhering to the same eye. London 

 Market 1848 (IF. Wing, see Baird). Youghal, Ireland 

 ( W. Thompson 1852). Observed on a sprat in Leith 

 Docks 1890 (J. Scott). Not uncommon on sprats 

 captured along the Lancashire coast (A. Scott). One 

 perfect specimen taken at Plymouth (Bassett- Smith) . 



A sample of six hundred sprats captured with the shrimp 

 trawl oil' Blackpool in 1910 yielded fourteen Lernseenicus 

 sprattse. The eye of one of the sprats examined had three 

 specimens of Lernseenicus fixed to it. The head of the 

 parasite is entirely buried in the tissues of the host, and can- 

 doI 1m- removed except by dissection. The parasite when 

 fixed to the eye appears to cause partial or total blindness. 



