^%T''] PROCEEDINGS OP THE NATIONAL MUSEUM. 155 



The circulur juuscles of the tentacles and disk are ectodcniial and com- 

 paratively Aveak. 



The lips are prominent, and are marked by delicate and numerous 

 stri;e, which are continued down the stomatodienm and ai)parent]y 

 corresi)ond approximately to the mesenteries. Two siphono<;lyphes 

 are present and are deep, the directive mesenteries being (comparatively 

 narrow. 



Thesphiucter inus<'le(Pl. xxii. Fig. L'4, .s^^//) is eiidodermal and ditfnse, 

 the endodermal muscle processes of the colninn being more numerous 

 and somewhat higher just below the margin than elsewhere. 



Tlie mesenteries are arranged in three cycles. The first cycle con- 

 sists of twelve ])erfect mesenteries, including two directives, the sec- 

 ond cycle likewise of twelve mesenteries, which are imperfect, how- 

 ever, and the third cy<-le of twenty-four mesenteries, which are quite 

 narrow and iinjterfect. All the mesenteries of the first and second 

 cy<les, with the exce])tion of the directives, are gonophoric. The Ion 

 gitudiiial muscles of the mesenteries are fairly well develojx'd, the 

 supporting process covering the entire non-gonoi»horic region of the 

 mesentery and l)eing of almost uniform height throughout. (PI. xxii, 

 Fig. 2.").) There is no special development of the parieto l>asilar muscle. 



In its general appearance B. occidua resembles very closely B. tia-- 

 di(r. I have been able, however, to examine some jneserved si)e(i- 

 mens of the latter obtained from the deeper water off our eastern coast, 

 and can state that there are marked differences in the anatol^iy of the 

 two species. For instance, B. iucdUv has the tentacles arranged in 

 only three cycles, and the parieto-basilar nuiscles upon the mesenteries 

 show a condition similar to what occurs in li. paiuiosa, to be described 

 below. 



It is possible that the form here described maybe identical wit li 

 Studer's ('78) B. l-crf/neleusis, which is described as having the ten- 

 tacles arranged in several cy(;les. We })osscss, however, no account of 

 the anatomical peculiarities of this form; and since the general shape 

 of the body differs decidedly from that of B. (wvldna, and there are 

 said to be seven cycles of tentacles in large specimens, I have consi<l- 

 ered it advisable to separate the two forms. I believe that in a case of 

 doubt it is ])referable tu consider the newer form a distinct species; 

 the union of Ibrms impro[)er]y separated is a much simi>ler matter than 

 the separation of forms err(«neously identified. 



A third form, with which B. occidua might possibly be identified, is 

 7>. midticorniSj of Verrill ('7i>). Andres ('83) places this form among 

 the doubtful Bunodida*, not being able to determine from A'errill's de- 

 scription whether it is truly a Bolocera or not. I have been able to 

 examine a specimen of it, however, and can confirm Verrill's assign- 

 ment of it to that genns, Tiie greater nunilx'r of its tentacles and 

 their much smaller dimensions show that it is distinct from B. occididt. 



