194 On the Development of the Pycnogons. 



finally the egg was traced to the mature animal, disclosing- a 

 very singular and unexpected mode of development ; for the 

 question at once arises, How do the larvse gain access to the 

 Zoophyte ? 



The development of Vallene, a genus which in some 

 respects resembles PhoxichiUdium, varies from that described 

 in certain important respects. The writer has only had an 

 opportunity of examining one of the larval stages in a speci- 

 men of Pallene brevirostris, the observations being unfortu- 

 nately brought to a somewhat hasty termination — the speci- 

 men being accidentally destroyed. It was, however, observed 

 that the young in a far advanced stage were attached to the 

 false feet of the female, in what manner could not be made 

 out, owing to minute size, and being very much crowded. 

 They possessed foot-jaws, a" rostrum, and three pairs of legs, 

 all of similar form to those of the adult animal; proving that 

 the young remain attached to the parent up to a late period of 

 their development, and perfect the growth of their limbs — or 

 most of them — whilst so attached, in such a manner as leads 

 one to suspect the development of the genus must be upon a 

 plan altogether distinct from others examined. 



In Nymphon the development takes a much simpler and 

 more easily understood plan. Several species have been 

 examined in their earliest or larval stage, at which time the 

 young animal is about the -nhjth. of an inch in length, and 

 scarcely so broad. It possesses two pairs of feet, which are 

 three jointed, the last joint being elongated and in the form of 

 a claw ; a rostrum and a pair of foot-jaws of large size, which 

 are quite out of proportion to the remainder of the animal : 

 the nippers are strong, the moveable finger usually overlap- 

 ping the other. 



A stout spine-like appendage is produced from the summit 

 of the first joint of each foot-jaw ; from the outside proceeds a 

 long slender filament, by which the larva is attached to the 

 oviferous mass for a short period after its birth : being of an 

 active habit, it soon frees itself, and is then carried about by 

 the motion of the water until it. finds a lodgment amongst the 

 stems of Zoophytes or the like, where it receives food and 

 shelter. Doubtless, large numbers are carried about by the 

 currents of the sea and perish, for although all of the Pycno- 

 gons are decidedly prolific, and each individual carrying ova, 

 must produce many hundred larvas in a season, the mature in- 

 dividuals are unquestionably rather rare. Mature Nymphons 

 are usually obtained amongst Zoophytes from deep water, but 

 appear to be very rare between tide-marks ; it is, therefore, 

 singular that the stage in advance of the larval ova, just de- 

 scribed, should only, have been found nestling amongst the 



