"LS'.)!i!'] PKOCEEDING.S OF THE NATIONAL MUSEUM. 153 



tweeii the two associated species. The hjiij^itudiiial muscles are only 

 moderately developed, and do not form a well-marked pennon. The 

 parieto- basilar seems to be weak. JSTo acontia occur. 



From the above description it maybe seen that this form is not read- 

 ily referable to any of the recognized families. On the whole, however, 

 it seems to approach more nearly the Autheadfe than any of the others. 

 The smootli column wall and the distribution of tlie re]n'oductive ele- 

 ments are points of similarity, but on the other hand the small number 

 of perfect mesenteries and the strong sphincter are decided differences. 

 The sphincter, however, is practically an endodermal one, and the 

 detinition given by Hertwig ('82) for the Antheadje does not exclude 

 the existence of a recognizable sphincter. In fact, in Actinia infecunda, 

 which he recognizes as an Anthead, a sphincter is present of such a 

 form that an excessive amount of differentiation wcmld not be called into 

 play to transform it into such a muscle as we find in Myonanthus. 



I think, accordingly, that it is advisable to refer this form to the family 

 Autheada^, regarding it as a somewhat aberrant form, which has the 

 jiower of completely retracting the tentacles, owing to the possession of 

 a well-defined sphincter, a character which has suggested the generic 

 name 1 have applied to it {ijucov = a knot of muscles). 



Family BOLOCElill).^^:. 



Actininaj with usually stout nouretractile tentacles, strongly con- 

 stricted immediately above their insertion into the disk, and hence 

 readily deciduous. Sphincter muscle endodermal, dilfuse, or in some 

 forms approaching the circumscribed type; the tentacles aiid disk fully 

 exposed in the contracted condition. With more than six i>airs of per- 

 fect mesenteries. 



Bolocera tueilia' discovered, in 1832, by Johnston, and later referred 

 by him ('47) to the genus Anihea may be taken as a typical example 

 of this family. Gosse ('60) established for it the genus Bolocera., and 

 separating it from the Antheadie, with which Johnston and Milne Ed- 

 wards ('57) associated it, placed it among the Bunodidje, in which clas- 

 sification he has been followed by Andres ('83). A study of the finni 

 occurring in the deep water off the eastern coast of the United States, 

 and which has been identified by Prof. Yerrill with B. tuediw, as well as 

 of other species of Tiolocera i'nnn t\ie Albatross (-(dlection, has demon- 

 strated that, so far as their anatomical peculiarities are concerned, these 

 forms are very different from the Bunodid.e, but stand in relatively 

 close affiliation to the Antheada^. The nature of the tentacles, how- 

 ever, and other structural characters, seems to be of sufficient import- 

 ance to warrant the establishment of a distinct family for them.* 



* It seems probable that Danielssen's ('90) Sideraciis is a llolocera, tbough the ex- 

 istence of an entloclermal sphincter woiihl pi'echule such an itlentificntion. It is to 

 be noticed, however, that Danielssen's iigure (PL Vil, tig. 10) hardlj- bears out his 

 assertion on this point. 



