334 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



placed on the apex. Second (fig. 6) and third pairs of 

 swimming feet nearly alike, the outer branches being 

 composed of three joints, and the inner of one only, which 

 has a slight constriction on its outer margin near the 

 apex. In the fourth pair (fig. 7) the outer branch is also 

 composed of three joints, but the inner branch is distinctly 

 two-jointed, there being a small apical joint carrying one 

 seta, and a moderately long basal joint. The fifth pair of 

 feet (fig. 8) consists of one broad lamelliform shield, due to 

 the complete coalescence of the basal joint of each pair. 

 The end of the coalesced basal joints is rounded, with a 

 slight concavity in the middle, on either side of which are 

 two short setae. The length of the plate is equal to nearly 

 two-thirds of the breadth at the widest part ; outer 

 branches very small, longer than broad, and bearing one 

 marginal and two terminal setae. Abdomen composed of 

 four segments, the first or genital segment being the 

 largest, the second or third segments are nearly of equal 

 length, the fourth segment is very small, being about half 

 the length of the second or third. Caudal stylets (fig. 9) 

 short and stout, the breadth being equal to about two- 

 thirds of the length. There are three setae on the extremity 

 of the inner angle, and one on the outer angle, with an 

 intervening space. There is also one small seta on the 

 outer margin near the base. The male is yet unknown. 

 In the same gathering as the last ; not common. 



This new member of the genus 'Leptopsyllus is easily 

 distinguished from previously described species by the 

 elongate joint of the inner branch of the first pair of 

 swimming feet, and by the structure of the fifth pair.* 



We have much pleasure in naming this species after 

 Professor Herdman. 



* This species has recently heen taken in the Clyde, off Millport, by 

 T. Scott. 



