GENERAL MORPHOLOGY 



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where this endite is divided into two endites [U and L*). Since the condition in 

 S. nototropis represents a stage prior to the division of the endite into two, the presence of 

 four pectinate setae on its distal end may be significant, as in the majority of species this 

 number is represented, there being two on each of the endites L^ and L*. A further point 

 of some significance is that in both species the maxiUiped is of the most primitive type. 

 On the other hand, the fact that, as far as can be made out, the endite (L-) of the 

 second segment appears to be directly continuous with the third segment of the axis is 



Fig. 2. The maxilliped, etc., of species of Serolis. 

 a, maxilliped of S. exigua, Nordenstam : x 87. 6, maxilliped of S. schythei, Liitken, S- x 20. c, maxilliped 



of S. schythei, Liitken, $: x 25. d, maxilliped of S. glacialis, Tattersall, 



65. e, maxilliped of 



S. glacialis, Tattersall, $: x 65. /, ventral view of left second thoracic appendage and its associated brood 

 lamella in a breeding $ of S. discoverii, n.sp.: x 35. 



more difficult to explain, and Dr Caiman, who has very kindly examined the prepara- 

 tions of the maxillae of these two species, is inclined to believe that the condition seen 

 is a secondary rather than a primitive one. 



The sympod of the maxilliped consists of a short coxa (C) and a large basis {B) pro- 

 duced distally into a large endite {B') ; the endopod or palp consists of three, sometimes 

 four, more or less lamellar segments. 



According to Hansen's description of the Isopod type of maxilliped, there is no exo- 

 pod ; but a plate-shaped epipod {E) is present, the proximal part {E) of which is marked 

 off by a transverse suture from the distal major portion (£") ; such a condition is figured 

 by him for Glyptonotus sibiriciis. 



