184 



ACT1NIAR1A 



Actinernus: I have (1918) shown that the type A. nobilis Verr. belongs to the Halcuriidae = Endo- 

 coelactiidae. For A. saginatus (Verr.), plebeius (Me. Murr.) and aurelia (Steph.), which are really Paractids, 

 we must establish a new genus 1 . 



Actinostola (type A. callosa Verr.) is a good genus, characterized by various authors and treated also 

 in this paper. 



Alloactis (type A. excavata (R. Hertw.)) is a synonym for Anthosactis and must be dropped (compare 

 Anthosactis p. 191). 



Ammophilactis (type A.rapiformis I^es.). The diagnosis, given by Verrill (1899 p. 213), shows that 

 the genus is different from Paranthus. "The reduced and feeble base" possibly indicates that the genus 

 does not belong to this family but to the Halcampidae. A closer examination is desirable. 



Antholoba (type A. reticulata Couthony = achates (Drayton)) is a good genus and characterized by 

 Hertwig (1882), Carlgren (1898) and Me. Murrich (1904). 



Anthosactis (type A. jan mayeni Dan.) is a distinct genus and easily identified (compare this paper). 



Antiparactis (type A. lineolata (Dana? Me. Murr.) = dubia n. nom. Verrill (1899 p. 212)). Con- 

 cerning this genus compare the genus Pycnanthus in this work, where a diagnosis of the genus is given. 



Archactis Verr. (type A. perdix (Verr.)) Verrill has (1899 p. 209) proposed this genus for Urticina 

 perdix. I have had the occasion to examine a specimen of this species, which the "Riksmuseum" in Stock- 

 holm has received from the United States National Museum, wherefore I can supply the statements of Verrill 

 concerning its organisation. In fact, it agrees very well with Antholoba. The sphincter is reticular and very 

 long in both genera, the longitudinal muscles of the tentacles are weak and ectodermal in Archactis as well 

 as in Antholoba, in the latter genus with a little tendency to be ecto-mesogloeal in their basal parts. The 

 radial muscles of the disc are of a similar appearance in both genera and are ecto-mesogloeal (I wrote 1898 

 p. 29 that these muscles are mesogloeal in Antholoba, it is more correct to designate them as ecto-mesogloeal). 

 The whole organisation of both species is the same; the appearance of the column, the undulated disc, 

 the numerous small tentacles and mesenteries, of which a great deal are perfect, the muscles of the mesenteries, 

 all agree. I have stated 1898 that the mesenteries of the first to the third orders are sterile in Antholoba. As far 

 as I can see, the fertile mesenteries only begin, also in Archactis, on the mesenteries of the fourth order (on the 

 other hand Verrill declares that all mesenteries in A. perdix, belonging to the first five cycles except the 

 directives, are fertile). Thus I think that A. perdix is an Antholoba, 



The nematocysts of the column of this species were 19 26 x about 2 ft, those of the tentacles partly 

 14 19 X I [i, partly 24 29 X 1,5 ft, partly 29 34 X 2,5^, those of the actinopharynx partly 14 17 X 

 1 ( T .5) fJ>> partly 24 30 X 2,5 //. The spirocysts of the tentacles were 19 X 1,5 // to 38 X 2,5 ;i. 



Aulorchis (type A . paradoxa R. Hertw.) belonging, according to Hertwig, to his family Liponemidae. 

 The exterior of this genus, the number and structure of the tentacles (the suppositional weak development 

 of these latter is certainly connected with their being more strongly contracted and more badly preserved 

 than in Sicyonis crassa], the structure of the oral disc and the appearance of the siphonoglyphes agree with 

 the corresponding facts in Sicyonis. Hertwig has not been able to determine how the mesenteries are grouped, 



1 Stephensen (1920!) p. 540) called this new genus Actinoscyphia. 



