II. Pelmatozoa. 5 



ing of the water- vessels. On the other hand the creatures will come up into the 

 air to avoid submarine dangers, and occasionally expose some of their rays volun- 

 tarily to an air bath. They will retreat from fresh into sea water much more 

 quickly than from the air. Several species exhibit traces of intelligence by letting 

 themselves fall from their place of attachment, when a stay there would be dange- 

 rous ; but in other cases the animal will remain exposed to the air , become dry, 

 and even die from histolysis. Starfishes imprisoned by pins fixed around them will 

 execute a great variety of movements of the most purposive character in order to 

 release themselves. Slight stimulation frequently causes auto to my, the de- 

 tached arm sometimes breaking up into several pieces , especially in Ophiurids ; 

 but if the connection of the radial nerves with the oral ring of an Ophiurid is 

 interrupted by section of the latter at the oral angles, autotomy is rendered more 

 difficult. C. is especially given to autotomy. If the centre is tetanised under 

 water, the arms fall off one after the other ; electrical stimulation of isolated rays 

 causes them to break, but not so readily as those of the entire animal. Sudden 

 plunging into warm water (37 C.) causes a vigorous movement at first and then 

 a general breaking up. Gradual elevation of the temperature is less destructive, 

 however. Regenerated arms of Ophiurids are more responsive to stimulation than 

 uninjured arms; but a broken ray will only form a new disc, when it retains a portion 

 of the nerve centre, so that the latter has a higher physiological value than in the 

 Asterids. Romanes' observations on the receptivity of Asterias rubens to light are 

 extended to many other species , but no trace of a colour sense can be distin- 

 guished. Ophiurids like Asterids have a sense of smell; and the olfactory nerves 

 must be in close relation with the coordinating centres as the animal will move in 

 a straight line towards the cause of stimulation. 



II. Pelmatozoa. 



(including Crinoidea, Cystidea, and Blastoidea) 



See also Hamannp), supra, p3, Hartog, supra, p3, and Preyer, supra, p 1. 



Carpenter (') points out various errors in the anatomical description of Antcdon 

 rusacea given by Vogt & Yung [see Bericht for 1886 Ech. p 6], referring more 

 especially to the relations of the calyx and chambered organ ; and he maintains 

 the existence of a sub-ambulacral nerve-vessel. Carpenter ( 3 ) also contests the 

 theory of Vogt & Yung's that the sacculi contain the zoospores of symbiotic Zoo- 

 xauthellae, and that the yellow cells of the ectoderm are their amoeboid spores. 

 Sacculi are not universally present, never occurring in Actinometra, though abun- 

 dant in Antedon at the same locality ; while they have a constant and definite 

 relation to the side-plates, when the ambulacral skeleton is fully developed. 



Carpenter ( 7 ) describes two Pentacrinoids from the Kara Sea which have 15 cirri 

 and no pinnules on some of their lower brachials. They are very robust, the larger 

 reaching 35 mm long, and probably belong to Antedon Eschrichti. 



Carpenter( 2 ) criticises the assumption of Walther, that the so called Embryonal- 

 Pinuulae, or 5 primary tentacles extended from the water- vascular ring of the 

 Crinoid larva, are homologous with the jointed pinnules which ultimately appear 

 at the sides of the arms ; and he disputes Walther' s identification of the clavicular 

 pieces of the radial axillaries as the primary "Embryonal Pinnulae of the larva. 

 [See Bericht for 1886 Ech. p 7]. 



de Loriol describes a young Apiocrinm roissyanus in which the perisomic plates 

 of the disc are preserved to a large extent. Between the rays they are continuous 

 below with the interradial plates resting on the angles of the first radials. The 



