109 



Fam. Acontiophoridae. 



Gen. Acontiophorus, Brady. 



86. Acontiophorus ornatus, Brady. 



(PI. LXXII). 

 Ascomyzon ornatum. Brady & Robertson, British Assoc. Report p. 197. 



Specific Characters. Female. Body on the whole of a more robust 

 appearance than in A. scutatus, with the anterior division broadly oval in 

 form and somewhat depressed, greatest width considerably exceeding half the 

 length and occurring behind the middle. Cephalic segment very large, nearly 

 twice the length of the trunk, and narrowly rounded in front, lateral corners 

 slightly produced. The 3 succeeding segments comparatively broad, with the 

 epimeral plates somewhat expanded an distinctly angular behind. Last trunkal 

 segment very small. Tail slightly exceeding in length Va of the anterior 

 division; genital segment about occupying half the length of the tail and 

 almost of equal width throughout, lateral corners of this and the succeeding 

 segment acutely produced behind. Caudal rami comparatively short, being 

 scarcely longer than they are broad; apical setae well developed and partly 

 finely plumose. Anterior antennae much more slender and elongated than in 

 A. scutatus, and composed of 16 well defined joints, the 3rd of vhich is 

 much the largest; proximal part of the antenna only slightly dilated and clothed 

 with strong partly ciliated setae. Posterior antennae likewise comparatively more 

 slender than in the type species, though of rather similar structure. Siphonal 

 tube scarcely extending beyond the anterior division of the body. Oral 

 appendages and natatory legs on the whole built on the same type as in 

 A. scutatus. Last pair of legs, however, af comparatively larger size, with the 

 proximal joint very broad, lamellar, and irregularly indented behind; distal joint 

 oval in form and provided with 5 ciliated setae of about equal length. 



Colour of the living animal not yet ascertained. 



Length of adult female 1.03 mm. 



Remarks. This form was at first recorded by Brady and Robertson 

 under the name of Ascomyzon ornatus, and was subsequently redescribed 

 and figured by the first-named author in his well-known Monograph as Acontio- 

 phorus armatus. As however the specific name ornatus is the older one; it 

 must be retained for the present form. The differences between this species 

 and A. scutatus are very pronounced, and at first I therefore believed them to 



16 Crustacea 



