152 Af'TINLE OF ALUATKOSS I'APLOKA'riONS M'lIURRICH. 



2*"". lis iiM'.S(>,!nI(i';i is latlicr thin, allowing' tlic stiaw-ycllow color of 

 the reproductive orj;ans to sliininicr tliroaj;li. 



The coluniii wall is smooth for the most part, except for the slight 

 folds caused by contraction. In the more intensely contracted si>eci- 

 mens in the upper part twenty-four lon<;itudinal folds were more or less 

 distinct, terminating abruptly at the margin; twelve of the folds are 

 smaller than, and alternate with, the other twelve. The ectoderm lias 

 been to a large extent macerated away from the column wall, but where 

 present it has the same color as tlic mesoglo'a. No trace of verrucas or 

 tubercles coidd be discovered. The mesoghea is much thicker than that 

 of the base and has a tibrous structure. It is not, however, stiff and 

 l)archment-like to the touch, but on the other hand rather soft and 

 t<mgh. Just at the margin, where the longitudinal folds of the con- 

 tracted specimens terminate, is a well-deveioped eudodermal sphincter 

 (PI. XXII, Fig. 23). It can hardly l)e classed either as "circumscribed" 

 or "diffuse," since, tlumgh well deiined, it is not connected to the 

 column wall by a distinct pedicle. It is rather intermediate between 

 these two varieties of sphincter, and resembles closely that form of 

 muscle whi(-h I have elsewhert^ ('8;>^() described for a si)ecies of I'ln/l- 

 laetis. I would suggest the application of the tcu^m "aggregated" for 

 this variety of muscle. Its appearance in cross section may be under- 

 stood by a reference to IM. xxii. Fig, 2.>. It is to be observed that anas- 

 tomes between the muscle processes ai'c not unfrciiuent, so that bun- 

 dles of muscle libers beconn^ enclosed within the nu^soghea. Imme- 

 diately adJacH'ut to the spliinctcr the ordinary ciicular muscles of the 

 colunni are hardly developed, Imt lower down they become stronger, 

 without, however, forming a second sjdiincter. 



The sphincter seems to occur Just at the margin, and apparently a 

 slight fosse exists between this and the outermost tentacles. No acro- 

 rhagi could be detected. The tentacles are numerous and arranged in 

 several cycles, but 1 could not ascertani their actual number. Their 

 color is the same as tliat of the cohwnn and tliey are of fair length and 

 rather slender. Theii- longitudinal musculature is not ind)ed<led in the 

 mesoght'a, resembling in this respect the radial muscles of the disc. 



The stonuitoda'um possesses two siphonoglyphes whose lower ends 

 are prolonged ai)parently some distance beyond the lower opening' of 

 the stomatoda'um. In conseijuence of this the directive mesenteries 

 are attached to the stonmtoda'um thnuighout a greater extent of their 

 length than are tlie other i)erfect mesenteries. There are, altogether, four 

 cycles of mesenteries, of which only the six jtairs forming the primary 

 cycle are ])erfect. The mesent<'ries of the fourth cycle are small, an«l 

 hardly project beyond (lie endoderm. All the mesenteries except those 

 of the fourth cycle and the directives are gonophoric. The reproduc- 

 tive <n\gans are very evident in dissected specimens, owing to their 

 bright orange color due to the i)i'escnce of numerous oil iilobules in the 

 ova and sperm mother cells. Tlic nicsmtcrial lilaments art^ not deeply 

 colored, as \n P. luno.sa. This forms a simi>lc |)oint of distinction be- 



