764 DR. W. T. CALM AN ON A 



by a shallow antero-lateral sinus from, which two converging 

 grooves run in on the dorsal surface. These grooves unite into 

 one on each side, but the resulting groove dies out before reaching 

 the middle line. A pair of intei-ocular chitinous rods are well- 

 marked, closely approximated in front, diverging posteriorly, and 

 united by an indistinct articulation with a nearly parallel posterioi- 

 pair. The paii-ed eyes are very small and close together near the 

 front margin. The unpaired eye could not be detected. 



The free thoracic region is not distinctly segmented ; it is of 

 equal width throughout and more than three times as long as 

 wide. 



The abdominal lobes are very long, narrowly lanceolate, and 

 cleft nearly to the base. No trace of furcal rami can be found. 



The antennules and antennte (fig. 3) are very minute and nearly 

 hidden from view under the in-turned front margin of the head. 

 The antennules, in particular, are very easily overlooked ; they 

 are not divided into segments but have a blunt lobe at the base 

 carrying a short apical tooth. The antennse are about the same 

 length, and consist of a stout basal part and a subglobular terminal 

 part separated from it by a constriction. 



The mouth-parts form a prominent cone (fig. 4). The two large 

 and well-separated lobes of the upper lip are unarmed. The lower 

 lip bears a pair of slender conical papillse ("maxillas" of Claus) 

 which project slightly from the opening of the mouth. The 

 mandibles are crescentic in form, with the concave edge very 

 finely serrated and the convex edge bearing a few teeth near the 

 tip. 



In front of the oral cone and continuous with it at the base is 

 a papilla, directed forward, having at its tip the opening of a duct. 

 This, no doubt, represents the sheath of the preoi-al "sting" of 

 Argulus, but no trace of the spine or sting itself could be detected 

 in the dissection of two specimens. At the base of this papilla 

 and of the mouth-cone are groups of very large cells, presumably 

 glandular, with deeply-staining nuclei. 



The suckers (first maxillae, second maxillae, or first maxillipeds 

 of various authors) axe placed close together in front of the 

 movith-cone, generally concealing altogether the preoi^al papilla. 

 In place of the usual radial supports, the whole of the membranous 

 border of the sucker is covered with discoidal scales (fig. 5). 



The maxillipeds (fig. 6) (maxillae of some authors) are very short, 

 very stout at the base, and tapering rapidly to the tip. They are 

 each composed of five segments, of which the second and third 

 have numerous pectinate or branched spines on the ventral and 

 anterior surfaces. The terminal segment bears two minute claws 

 and a process which lies alongside of them. 



The successive pairs of legs (figs. 7-10) are set wide apart from 

 each other along the sides of the thoracic region. The rami are 

 in all cases shorter than the protopodite and carry only a few 

 short setae ; there is no flagellum on any of the legs. In the first 



