ACTINIARIA 



87 



the spirocysts and the nematocysts of several specimens I have given below in /i, a. typical nematocysts, 

 aa. nematocysts with discernible basal part to the spiral thread, b. spirocysts. 



i) sp. from Scoresby Sound, size see above! 2) sp. from Hurry Inlet, length about 4cm, breadth 3 cm. 

 3) sp. from NW. of Behring Sound, length 3,8 cm, breadth 1,2 cm. 4) sp. from the Ingolf-Exp. size see above! 

 5) a small specimen from Hurry Inlet, breadth 0,3 cm. 6) sp. from Scoresby Sound, length 1,8 cm, breadth 

 I cm. 7) sp. from the German Tiefsee-Exp., size see above! 8) sp. from the Graham region, length 4,5 cm, larg- 

 est breadth 1,3 cm, length of the tentacles 1,4 cm. 9) kerguelensis. 10) clavus. 11) clongatus, size see above! 

 12) sp. from Naples. The dimensions of the nematocysts of the specimen 9 are only approximate, as they 

 refer to old measurements from 1897. 



If we disregard the specimens 11 and 12, in the column of which I have not found any large nema- 

 tocysts, the other specimens do xexy well agree. The nematocysts of the specimen from Naples, however, 

 are a little different in size, wherefore we might possibly consider it as a distinct variety to which also elon- 

 gatus probably belongs (compare below!). The nematocysts of the column are few in the middle part of the 

 body, in the distal part numerous. The mesogloea is of ordinary' thickness. The endodermal circular muscles 

 are not very much developed and form no separate sphincter. The sphincters which are mentioned by Hert- 

 wig in clavus and the distal sphincter, which Appellof stated to be present, are nothing but local phenomena 

 of contraction. The ectoderm of the tentacles is verj' high, the ectodermal muscles a little ramificated, but 

 low, and the mesogloea of ordinary thickness ; the endoderm is the thinnest layer. The ectoderm of tlie actino- 

 pharynx contains numerous, large, typical nematocysts, while the other nematocysts are few or very rare. 

 It is devoid of ectodermal muscles. The siphonoglyphes are but slightly differentiated, as regards their histo- 

 logic structure. 



There are 6 pairs of mesenteries, of which 2 pairs of directives; they are all perfect and fertile. In 

 younger specimens the 8 " Edwardsia-va.es,&r).ttnQs" are stronger than the other mesenteries, what has been, 

 observed by Hertwig as well as by Appellof, and what also I confirm. The longitudinal muscle-pennons 

 are very strong, with high, and especially in older specimens, very ramificated folds in the reproductive re- 

 gion. In younger specimens the folds are less numerous in the reproductive regions or in the part where such 

 folds are afterwards developed, but they are thicker than in older specimens. Thus the pennons of the "don- 



