15S ACTINL'E OF ALBATROSS EXPLORATIONS MCMURRICH. 



on short ])ro('osscs ol' incso^ld'u. On the ciMloccelJc face of tlu' iiicson- 

 tory near its instMlimi into the coliinrn wall arc miisclo ]»rocoss('s boar- 

 ing lon.ii'itudinal iniisclcs [Ini), but llio greater portion of the surface is 

 covered by a well marked layer of transverse muscles (tm), amongst 

 wliicli, however, some longitudinal fibres may be detected. This trans- 

 verse layer covers about two thirds of the surface, Ijuttlie thiid adja- 

 cent to the stomatodjeum is occupied by the moderately developed 

 longitudinal muscle-])ennon {bii). The arrangement appears at first 

 sight to be the normal relations rc\'ersed, so far as the faces of the 

 mesentery aie concerned, and to a certain extent this is the case. 

 The greater i)ortion of what normally would be exoctelic transverse 

 nnisculature has become longitudinal, wliile tlieendoccelic longitudinal 

 musculature has to a large extent become transverse. The longitudi- 

 nal muscle ])ennon, an<l the ]>arieto basilar muscle still, however, retain 

 their noimal relations. , 



Ahistological i)oint was well shown in the]»rei)aratiousof this form, on 

 account of the sjjecimens having umlergone a certain amount of macera- 

 tion in the ])reserving alcohol. Delicate mesoglo'al filaments can 

 leadily be seen to <'xtend from the muscle ]»r()cesses out between the 

 cells, l)oth of the ectoderm and the endodcMin. 1 have called attention 

 to this fact in the case of ^^>7Vo////*^sw^;/r/•/r7^//^s■ ('!>()), and have since 

 ol)served it in numerous forms, so that it is prol)al)l,\- a normal arrange- 

 ment. 



12. Bolocera bievicornis, s]>. iiov. (Sco Apprinlix, ]>. 209.) 



ri. XX III, Fijis. 31-33. 



No. 730. Stiition 2839. L;it. 33^ OS' N., louij. 118^' 10' W., Ill f'uthoins. Two speci- 

 mens. 

 This interesting foiin wasdre^lged in liie same locality as 1*. pannoHa. 

 It is represented in the collection Ity two six'cimens, one of Avhich is 

 apparently full grown, while the other is e\i(lently young. 'I'he base 

 is circular in outline and adherent. It measures in the large specimen 



9cm 



The column wall is]»ent downwards, so that (he margin is almost level 

 with the base, and (he whole exi>anse of (he disk is exposed. Thecolumn 

 is marked by nnmerons l(»ngitndinal lines, extending from the lim- 

 bns to the margin, wlu're they terminate in a well marked circular fold. 

 Apparently the uit])er i)(»iti«)n <»f the column is furnished with verruca*, 

 but owing to the somewhat imperfect preservation of the column ecto- 

 derm it is irapossibh^ to be certain on this point. The mesoghea of the 

 column is moderately (hick, and on i(s inner surface is lichly folded, 

 so that the ciicular nuisculature is relatively strong. In the region of 

 the circular fold, which forms tlu^ margin, the muscle ])rocesses are 

 hmger aud more closely aggregated than elsewhere, forming a well- 

 marked endodermal sphincter of the dilVuse tyi)e (PI. xxiii, Fig. 31). 

 Below the sphincter the wall is thinner than elsewhere, aud has the ap- 



