Se^f- evisceration in the Asteroidea. 283 



wliile a sixth mass of cseca issued from tlie wart-like pro- 

 tuberance lialfway down the upper surface of the super- 

 numerary sixth ray. Each of the five normal rays was 

 ruptured for a length of 5 mm. on the upper surface close to 

 the tip, and from these small slits protruded the whole caecal 

 contents of the ray still paired by their basal connection. The 

 animal thus eviscerated was in a livoly condition. It moved 

 across the dish with its tube feet in active motion and the 

 dermal branchiae exserted, and when turned over on its back 

 was able to quickly resume its normal position. The rays 

 had become flattened and in places even concave by the 

 withdrawal of the ca?ca. This individual lived for three days 

 after the rejection of its cseca, and on the 22nd April, the day 

 after this rejection, a mass of orange gonads was seen to 

 issue from the ruptured tip of one of the arms. Though 

 changed from time to time, the water in which this specimen 

 was ke])t became rather stale at intervals, as it did with the 

 other specimens dealt with in these notes. 



The actual process of self-evisceration, which I had no 

 opportunity of observing in this six-rayed individual, 1 was 

 enabled to watch closely in the larger and normally tive-rayed 

 specimen taken on the same day, the 17th April. At 11 A.M. 

 on the 23rd April the first sign of extrusion was noticed. 

 A small lump of tawny ceeca made its appearance on tiio 

 upper surface and near the tip of one of the arms. Three- 

 quarters of an hour later this extrusion was completely 

 withdrawn and no trace of rupture could be made out on 

 examining the tip of the arm with a hand lens. No further 

 extrusion took place that day, but at 8 A.M. on the following 

 day, 24th April, a mass of caera as large as a pea was 

 observed at i\\Q extremity of one ray and a much smaller 

 mass at the tip of a second and adjacent ray. Half an hour 

 later the smaller mass was found to have doubled in size and 

 at 10 A.M. a fairly large extrusion appeared at the end of a 

 third ray, adjacent to those already luptured. Nearly two 

 hours later, at 11.4.5 A.M., measurements were taken of tiie 

 caeca extruded from the three contiguous rays, when the 

 lengths were found to be 4, 8, and 11 millimetres respectively. 

 About this time swellings and pale bands and blotches were 

 seen to travel very slowly along the ruptured arms and to 

 come and go on different parts ^ the dislc, suggestive of the 

 slowly propagated swellings which [)recede self-evisceration 

 in certain Holothurians. 



Further measurements of the extruded caeca made at 

 12.45 P.M. the same day gave lengths of 4, 10, and 16 

 millinielres, and about the same time orango-coloured gonads 



20* 



