Mr H. Goodsir on the Sexes of the Cirripeds^ S^c. 337 



gists of six segments, and the last has the extremity armed with two 

 styles, which are each composed of a single plate, the extremity being 

 armed with five very long spines. 



The organs of the mouth in this animal, from its small size, I have been 

 unable to make out. 



The alimentary canal consists of a simple straight tube. The breath- 

 ing is carried on doubtless bj' means of the spines and setoc, which arc 

 so numerous on the foot-jaws. 



This species is distinguished from C. australis by the two long spines 

 which arise from the twenty-second and twenty-third segments of the 

 external antennse ; the extremities of these antennae in M. Vauzeme's 

 species having only one spine, or, according to that author, bifid. The 

 foot-jaws also differ in the two species, but especially so in the third 

 pair ; these organs in C. septentrionalis presenting very much the ap- 

 pearance of a human hand with the index and little finger flexed, as it 

 were, on the palm, whereas those of C. australis consist of three branches 

 arising from each side of a stem. 



SECT. IV. — ON A NEW GENUS AND SPECIES OP CRUSTACEAN. 



The animal which is now to be described, is met with occasionally 

 among the Maidre. It is solitary in its habits, a single specimen being 

 only seen now and then, owing, however, to its brilliant metallic colours, 

 is easily observed as it shoots along the surface of the water. 



The structure of this animal is such as to require the formation of a 

 new generic situation in the family Pontia of M. Edwards. The deci- 

 sion of this question was difficult, owing to the apparently contradictory 

 characters in the structure of the animal. I at one time placed it in M. 

 Edward's restricted genus Monoculus, from the structure of the an- 

 tenna} and eyes. After a minute examination, however, of several spe- 

 cimens, I was enabled to analyze the structure of the animal more cor- 

 rectly. It forms the, or one of the, connecting links between the two 

 families, namely, Pontia and Monoculus. It is connected more nearly 

 to Pontia by means of the structure of the body, the foot-jaws, the am- 

 bulatory legs, the abdomen, and the eyes ; to Monoculus by means of 

 the antennae and the eye. 



Upon looking cursorily at the organs of vision, the observer would 

 suppose that the animal was really Monoculus. This arises from the 

 circumstance of the eyes being situated at the superior extremity of a 

 tubular organ, which is apparently for the purpose of assisting the sight. 

 The eyes are situated on the dorsal aspect of the body, near to the an- 

 terior extremity of the body, and almost between the origin of the an- 

 tennae. 



GENUS IREN.ilUS.* (MlIII.) 



A large tubular organ arises from the lower or abdominal surface of 

 the body, in the superior extremity of which the organs of vision are 

 situated ; the right antenna) very much swollen a little behind the middle. 

 Foot-jaws ten in number. 



* St Ircnaeus to whom the church of Kilrennvor Ironic in Fife was dedicated. 



