( 33G ) 



^he genus Cetochihis belonging to the order Copepoda and the fa- 

 mily Pontia ofM. Edwards. By Henry D. S. Goodsir, Esq.,- 

 Conservator of the Museum of the Royal College of Surgeons, 

 Edinburgh. Communicated by the Author, with Plate. 



(Continued from p. 104.) 



Cetochllus septentrion^lis, the species now to be described, is about 

 a line and a half, or two lines long, of a bright red or scarlet colour, and 

 slightly translucent. The body is divided into two great parts, the 

 capito-thoracic, and the abdominal. The superior antennae are almost 

 obsolete, and are composed of two articulations, the last of which is 

 about four time» as long as the first, and is lanceolate. The inferior, or 

 external antennae, are very long and slender, being longer considerably^ 

 than the body of the animal. Each of them is composed of twenty-four 

 articulations ; the first of these is the largest ; the twenty-second and 

 twenty-third are each armed with a very long setum, which is pointed 

 upwards and inwards. 



The eyes are two in number, but very minute. The foot-jaws are ten 

 in number. The first (Plate YI. Fig. 12.) consists of two branches arising 

 from a common peduncle ; one of these consists of a single articulation 

 only, which is considerably bent, flattened, and which tapers to a point; 

 it is armed with long simple seta) on its superior edge ; the other part of 

 this foot-jaw is biarticulate, the first joint being the longest ; it is armed 

 with a long single spine at its extremity ; the second articulation is about 

 lialf as long as the first, and its extremity is armed with a number of very 

 long setae. 



The second pair of foot-jaws are connected with the mandibles, and 

 are also composed of two parts arising from one common peduncle, and 

 composed of the same number of articulations as the last, but smaller. 



The third pair of foot- jaws are very curious, and if they were free of 

 the setee would present very much the appearance of a human hand with 

 the index and little fingers concealed. 



The fourth pair of foot-jaws are composed of one flattened scale-like 

 joint, with a great number of long setoe arising from its inner edge. 



The fifth pair of foot -jaws are composed of four joints, the last of which 

 is very long, an|i armed on its inner edge with long spines. 



The ambulatory legs are ten in number, and are bipartite. They 

 arise from the last five thoracic segments of the body. The peduncu- 

 lar portion of the leg consists of two segments. The external portion 

 of the leg is composed of four articulations, the last of which is long, 

 claw-like, and serrated on its inner edge. The internal edge of the third 

 articulation is armed with a great number of very long spines ; the in- 

 ternal portion of the leg is composed of four very short segments ; it is 

 as long as the two first segments of the external portion. 



The abdominal portion of the body is much smaller than the thoracic, 

 not being nearly so thick, and is generally in an erect position ; it con- 



