MOEPHOLOGY OF CYCLOPS. 13 



again serrated, followed proximally by a conical hair, pale-bordered distally, and a 

 conical setose plume near the base. 



Palp inserted on ventral anterior border of basal joint, just before its distal end ; 

 squarish and continued into a terminal shorter ramus and a lateral longer ramus 

 (exopodite ?), both oblong. Basal part bearing a plume on its outer preaxial edge. 

 Terminal ramus bearing a somewhat falciform saw, serrated only on inner concave edge, 

 and two rather longer plumes. Lateral ramus bearing three long strongly setose plumes. 

 The two rami of the palp are not at all articulate, and are what Lankester terms ' inar- 

 ticulate phyllites.' The maxillae lie turned forwards beneath the paragnathse, which they 

 usually underlie, and in normal extension do not come far from the body. 



Proper Muscles of the Maxilla. — A strong flexor of the distal joint (in. Jl. 2 ), taking 

 origin on the outer side of the basal joint ; an extensor of the distal joint (m. ex. 2 ) takes 

 origin just beyond this ; and two small muscles run to the base of the palp. 



Extrinsic Muscles of the Maxilla (PI. III. fig. 5). — These are of unusual complication, 

 having origins in the free entosternite, the postmaxillary apodeme, and the dorso-lateral 

 regions of the carapace. I believe the following is a correct classification by function : — 



Long adductor obliquely inwards, downwards, and forwards from latero-dorsal region 

 of carapace to anterior and inner angle of base. 



Short adductor from side of carapace to same insertion. 



Long abductor directly downwards and forwards from its insertion near top of carapace 

 behind long adductor to outer side of base. 



Lateral abductor from side of carapace to same insertion. 



Short abductor from entosternite to same insertion as last. 



Flexor (?) from " toe " of postmaxillary apodeme to anterior side of basal joint. 



Extensor (?) from same insertion to posterior side. Doubtless the adductors and 

 abductors also contribute to flexion and extension respectively. 



V. Maxilla of second pair, Maxilliped. — The peculiarity of this limb is its division down 

 to the base into two rami, with distinct extrinsic muscles. Claus figures them correctly 

 as inserted into a single arthrodial cavity, imperfectly divided by a peg on the posterior 

 side ; but his interpretation that they are connected by a chitinous bar is erroneous. As 

 mentioned above, they are completely separate. In Cyclopida they arc inserted nearly 

 at the same level, the area for the outer ramus being prolonged inwards anteriorly in 

 front of the inner ; in many Copepoda this is so exaggerated that the outer is completely 

 in front of the inner, so that they are often termed anterior and posterior maxillipeds *. 

 I shall describe these two rami, each with its musculature, as outer and inner maxillipeds 

 respectively. 



Y a. Outer Maxilliped (PI. I. fig. 6). — Basal joint elongated and strong; at base of 

 trapezoidal section the anterior side longer than the posterior ; above rather narrowed 

 and compressed from before and without ; marked about one third its length up by a 

 transverse interruption of its thickened cuticle to form an imperfect joint ; outer 



* Van BeDeden, according to Gerstacker, regards them as distinct limbs (Bronn's ' Thierreich,' Bd. v. Abth. 1). 



