FROM THE GULF OF GUINEA. 10] 



elongate, larg-cr tlian the basal joint and furnished with six plain setae — two apical, two 

 suhapical, and two on tlui lower half of the outer margin (fig. 10). Caudal stylets very 

 short ; the basal part of the principal caudal setae is distinctly g-il)bous, as shown in 

 fig. 41. Clans also, op. cit., describes and figures this character of the tail-setae. He 

 obtained Thalestris fovficula at Messina. 



Genus Ilyopsyllus, Brady & Eobertson. 

 IlyopsyUus, Brudy & llobcrtsou. Aim. & Mag. Nat. Hist. s. 4, vol. xii. p. 132 (1873). 



Ilyopsyllus affinis, n. sp. (PI. XI. figs. 4-17.) 



Length "5 mm. Body tumid, .similar in form to Ilijopsyllus coriaceus, B. & E,. ; 

 rostrum broadly triangular, furcate at the apex. 



Anterior antenna? S-jointed in the female, 8-jointed in the male ; the produced upper 

 distal portion of the dilated liasal joint is more or less hispid and furnished with several 

 spiniform seta? ; a curved fold fringed with long stout serrse occurs near the distal end 

 of the base, and extends from the upper margin downwards about two-thirds the breadth 

 of the joint. In the female the three apical joints are of nearly equal length. The 

 proportional lengths of the joints are nearly as shown in the formula : — 



Female : 20 . 10 . 8 . 7 . 8 



1 2 3 4 5 6 7 8 



llalc : 8 . 20 . 5 . t) . 7 . lU . . .5 



The third and fourth joints in the male are each provided with a long " olfactory " 

 appendage, as are also the female antennae, and these olfactory filaments appear to have a 

 small joint near the proximal end, as shown by the figs. 4 and 5 ; posterior antennte and 

 mandibles nearly as in Ilyopsijllus coriaceus. Eig. 10 represents what appear to be 

 the maxillae and oral aperture. Figs. 11 and 12 represent what appear to be the 

 anterior and posterior foot-jaws as observed in the dissections of the animal. The first 

 four pairs of swimming-feet resemble those of Ilyopsyllus coriaceus, except that the 

 middle joint of the outer branches of the first pair is somewhat longer than either the 

 first or third joints. Fifth pair small, simple, obliquely truncate at the apex, with the 

 lateral angles somcAvhat produced and bearing each a smtill spiniform seta, and a 

 similar seta springs from the distal half of the outer margin ; a transverse curved row 

 of small spines extends nearly across the basal part of each foot (lig. 15). Abdominal 

 segments fringed with stout cilia. Caudal stylets short, breadth about equal to the 

 length, each furnished with two very short set;© and a long one, which is slightly 

 spathulate at the base. 



Habitat. In a shore lagoon at Sao Thome Island, among species of Conferva. 



