THE CUM ACE A. 309 



developed abdominal limbs, though they appear late. It is 

 interesting to find that the females, in this respect, retain 

 more of the larval character than the males. 



( )n examining the apparent rostrum with care, it is found 

 to be divided along the middle line by a fissure which runs in 

 front of the eye (which is here single and sessile), divides into 

 two branches, which run backward and outward, and termi- 

 nate before traversing half the length of the carapace ; they 

 thus cut off a median lobe, bearing the eye at its apex, from 

 two lateral processes. The lateral processes are simply pro- 

 longations of the antero-lateral regions of the posterior di- 

 vision of the carapace (as it were the antero-lateral angles of 

 the carapace of My sis, excessively produced and meeting in 

 the middle line) ; while the middle lobe corresponds, I believe, 

 with the cephalostegite of the carapace in ordinary Podoph- 

 thalmia, the insertions of the mandibular muscles occupying 

 their normal position, toward its posterior boundary. The 

 hinder part of the carapace will therefore correspond with the 

 terga of the three anterior thoracic somites, the five posterior 

 ones being, as has been seen, free and movable. 



The five anterior pairs of thoracic appendages are con- 

 structed much on the same plan as those of the tSchizopoda ; 

 the three posterior have no exopodite. In the female, the 

 sixth abdominal somite alone has appendages, but in the male 

 the two anterior abdominal somites are provided with styles. 

 ( )\ i<2:erous plates are attached to the fourth, fifth, and sixth tho- 

 racic appendages in the female. The structure of the head is 

 peculiar. No ophthalmic sternum nor ophthalmic peduncles 

 are discernible, the single, or closely approximated two, eyes 

 being sessile on the median line on the superior surface of 

 the head. The coxopodites and basipodites of the antennules 

 and antennae are bent down almost at right angles with the 

 axis of the body, and appear to be connate, or confluent, with 

 their sterna. The succeeding joints are free and pass for- 

 ward, the antennules being much longer and stronger than 

 the antennae in the females, while in the males the antenna 1 

 are very long; the labrum is large ; the mandibles strong and 

 unprovided with a palp. There is a distinct metastoma, and 

 the maxillae are delicate and foliaceous. A papillose bran- 

 chial plate is attached to the base of the first thoracic append- 

 age. The surface of many parts of the body in some species 

 exhibits a very peculiar sculpturing, singularly like that ex- 

 hibited by the Eurypterida. 



As in the Podophthalmia^ the heart is short or mod- 



