MUSEUM OF COMPARATIVE ZOOLOGY. 109 



The young were taken from the adult by cutting off the disk, leaving 

 the arms intact. By removing the disk in this way it was found that 

 the young remained in it, and when left for a short time in pure 

 water the older specimens crawled into view. Lyman * has recorded 

 that adults found near Bordeaux often in confinement voluntarily cast 

 their disk, from which the orange-colored y^ung emerge. The older 

 forms of the young can voluntarily escape from the disk through the 

 genital slits. Those which have an umbilical attachment, particularly 

 the bilateral larvae, must be teased from the ovarian attachment by 

 means of needles or small scalpels when required for study. A deli- 

 cate dissection is necessary to separate the larva from the inner wall of 

 the body without harm to the attached young. 



The larvse were studied alive. Many were killed in weak alcohol, 

 hardened in 93° alcohol, placed in chloroform for three minutes, and 

 then mounted in Canada balsam. The treatment with chloroform 

 brought out the plates with success. Staining in borax carmine showed 

 the water-tubes, but obscured the plates. 



Young Amphiurse were found from the first of August until the end 

 of September, with little reduction in numbers except in the last week. 

 The number of young from diflerent adults varied. Ordinarily a gravid 

 adult would have from ten to fifteen (generally ten) free young, and 

 possibly several bilateral larvae at the same time. The older young live 

 free in the body cavity, generally with the arms coiled up, but often 

 with an arm extended through the genital slit. Parturition is moder- 

 ately slow, sometimes rapid. The young when born are orange-colored 

 on the disk, with Avhitish-colored arms, and with plates less firmly 

 articulated than in the adult. When once born, young were not seen, to 

 return to the pouches, nor were they cared for by the adult. They did 

 not cling to the mother after birth. Especial attention was directed to 

 this observation, for I was familiar with the figures given by Thomson f of 

 young Ophiurans of-another genus clinging to the disk of the adult. 



The young Amphiur£e which voluntarily left the parent were of course 



* Op. cit., p. 123. 



t Notice of some Peculiarities in the Mode of Propagation of certain Echino- 

 derms of the South Sea, Journ. Linn. Soc, XIII. Dr. W. Stimpson {Proc. Bost. 

 Soc. Nat. Hist., IV. p. 2'26) found in Charleston, S. C, small Ojjhiurans clinging 

 to the arms of Hemipholis cordata, Lym. {Ophiolepis elongata, Say). He regarded 

 them as the young of the animal to which they were clinging, and thought that they 

 "correspond" to the genus " Ophionyx, M. T." 



Lyman (Challenger Ophiuroidea, p. 157) describes and figures two stages of the 

 young Hemipholis which he finds clinging to the arms and disk, and "suspects" 

 that the genus is viviparous. 



