new and rare Crustacea from Scotland. 145 



Hab. Vicinity of the Bass Rock, Fivtli of Forth. Hitherto 

 only one specimen, a female, has been obtained. 



Bemarks. The proportionally large and tumid cephalo- 

 thorax gives this species a curious and striking appearance, 

 that at once distinguished it from any of the other Copepoda 

 observed by us. It possesses all the characters of a Derma- 

 tomyzon^ except that the anterior antennge are apparently 

 only seventeen-jointed ; the second joint, however, is pi"o- 

 bably composed of three coalesced joints, so that the dif- 

 ference in this respect is trilling. It differs also in the 

 abdomen being composed of only three instead of four seg- 

 ments, and so far it agrees more closely with Asterocheres, 

 Boeck, than with Dermatomyzon, Claus. The Forth specimen 

 would thus appear to form an intermediate link between 

 these two genera, but with a closer affinity to the last. 



AcontiopJiorus elongatus, sp. n. (PL IX. figs. 15-20.) 



Length 1 millim. (•;73- of an inch). Cephalothorax and 

 abdomen elongate ; the abdomen slender and equal to about 

 two thirds the length of the cephalothorax. Anterior 

 antennae slender, seventeen-jointed ; the fourth, fifth, sixth, 

 and eighth joints are shorter, and the first and last longer 

 than any of the other joints ; the formula shows their pro- 

 portional lengths — 



24 ■ 12 . 14 ■ 6 . 6 . 6 . 9 ■ 6 . 8 ■ 14 . 12 . 13 . 13 . 14 . 14 . 14 . 24 

 1 2 3 4 5 (J 7 8 9 10 11 12 13 14 15 16 17' 



The posterior antennge are three-jointed, and a very small 

 secondary branch springs from near the end of the elongate 

 basal joint ; end joint small, and furnished with a long, 

 slightly curved, and slender terminal spine and a small mar- 

 ginal seta. Mandibles extremely long and slender, being 

 about equal in length to the elongate siphon; the siphon, 

 which reaches to near the end of the cephalothorax, consists 

 of two slender filaments of equal length, one of which has 

 a ring-like structure and is armed with a small apical stylet ; 

 the basal part of the siphon is stout and cone-shaped, and 

 encloses for some distance the proximal ends of the filaments 

 (fig. 18). MaxilltB two-branched — one branch stout and 

 conical in shape, and furnished with one short and two long 

 setaj 5 the other branch narrow, not half the length of the 

 first, and bearing three setaB of unequal length. Anterior 

 and posterior foot-jaws somewhat like those of AcontiopJiorus 

 scutatuSj Brady and Robertson ; but the last two joints of 

 the posterior foot-jaws are proportionally much longer than 



