of the Fishery Board for Scotland. 261 



appears to be composed of two or three coalesced joints, as shown in the 

 formula, which gives approximately the proportional lengths of the 

 joints : — 



40 • (19 • 10 • 7) . 8 • 10 • 12 • 16 • 9 • 9 ' 16 * 12 • 12 • 12 • 12 • 16 ' 18 • 8 • 26 • 

 1 • ' 2 ' • 3 • 4 • 5 * 6 • 7 • 8 ' 9 • 10 " 11 • 12 • 13 • 14 • 15 • 16 • 17 ' 



Mandibles stylet-shaped, stout, and elongate. The mandible-palp consists 

 of a single oblong joint, the length of which is greater than twice the 

 breadth ; aud three stout, moderately long and nearly equal setae spring 

 from its truncate apex. The maxillae are composed of a sub-triangular 

 primary part, furnished with three apical setae, and a narrow cylindrical 

 secondary part, provided with four setae at the apex. The anterior foot- 

 jaws have the basal part stout, but the end is slender and curved, and 

 forms a claw-like appendage. The posterior foot-jaws and swimming-feet 

 are somewhat like those of Dermatomyzon nigripes (Brady and Robertson). 

 The fifth pair are simple and two-jointed. The first joint is short, and its 

 breadth is about equal to twice the length, and a seta springs from its 

 upper distal angle. The second joint is longer and narrower, the length 

 being about twice the breadth. It is furnished with two apical setae. 

 The caudal stylets are nearly as long as broad, and are equal to the com- 

 bined lengths of the last two abdominal segments. 



Habitat. — Vicinity of the Bass Rock. Rare. 



The very tumid form of the cephalo-thorax and short abdomen give to 

 this species a very curious and striking appearance that at once dis- 

 tinguishes it from all other Copepods known to us. 



Genus Acontiophorus, Brady (1880). 



Acontiophorus elongatus, T. and A. Scott. 



1894. Acontiophorus elongatus, T. anl A. Scott (31), p. 145, pi. 

 ix. figs. 15-20. 



Description. — Female. Length, 1 mm. (~ of an inch). This is an 

 elongate form. The abdomen is slender, and equal to about two-thirds of 

 the length of the cephalo-thorax. The anterior antennae are slender, and 

 composed of seventeen joints. The proportional lengths are as follow : — 



24 • 12 • 14 • 6 • 6 • 6 ' 9 • 6 • 8 • 14 • 12 ■ 13 • 13 • 14 • 14 • 14 * 24 • 

 1 • 2 * 3 • 4 • 5 • 6 " 7 ' 8 • 9 • 10 • 11 • 12 ■ 13 ' 14 • 15 • 16 • 17 • 



Posterior antennae and mouth organs are nearly as in Acontiophorus 

 scutatus (Brady and Robertson). The mandibles are extremely long and 

 slender, being about equal in length to the elongate siphon. Foot- 

 jaws and swimming-feet also somewhat similar to those of Acontio- 

 phorus scutatus, but the fourth pair are armed with remarkably broad and 

 stout dagger-shaped spines on the exterior margins of the outer branches, 

 and broad sabre-like terminal spines on both branches. The fifth pair 

 consists each of a single elliptical joint, furnished with three apical setae. 

 Caudal stylets very short. 



Habitat. — Vicinity of the Rock. Frequent. 



Remarks. — The slender form of this species, and especially of its 

 elongate and slender abdomen, enables this species to be distinguished 

 from any other described Acontiophorus. It differs from the typical 

 Acontiophorus scutatus in the posterior antennae having only one long and 

 slender spine at the apex instead of two lancet-shaped apical spines, but 

 otherwise the species now described is a true Acontiophorus. 



