LUCERNARI^ AND THEIR ALLIES. 21 



proboscis, it will be seen that the partitions must be inclined at an an<^le of forty- 

 five degrees to tliese planes, since they trend perpendicularly from the middle of 

 each flank of this proboscis toward the uuibellar sinus wliicli lies nearest to and 

 opposite said flank ; and, moreover, it follows tluvt the midline of each of the four 

 compartments of the general cavity is coincident with cither the one or the other 

 of these planes. The lateral extent of these compartments is limited only by the 

 narrow partitions, but that is enough to define exactly their relation to the angles 

 of the proboscis, the butresses (^'') of the latter projecting in strong ridges over the 

 middle of the compartments, and in fact forming, in part, the front wall of tlicir 

 proximal ends. Thus it is evident that the general cavity (4'') cannot be separated 

 by any demarcation from the post-buccal chambers {\^'^). The peripheral extent of 

 this chamber is limited only by the conjunction of the anterior and posterior parietes 

 of the umbella, and it even is prolonged into the tentacles and adherent organs, 

 both the latter and the former being hollow to their tips. 



49. Tlie organs which are included in these compartments belong to but one 

 system — the repwductive. They have already been mentioned (44:) as dark, trian- 

 gular pavement-like bodies ; but their exact relation to the walls of the imabcUa 

 has not been stated, and tlierefore one of the most important morphological features 

 of the whole animal remains to be delineated. That they are totally Avitliin the 

 cavity embraced by the front and back faces of the umbella, and that they have no 

 communication with the exterior except through that cavity, might be sufficient 

 to affirm before the time of certain recent discoveries in regard to the relative 

 position of the reproductive organs, or of the region of the reproductive process, 

 but at present it is absolutely indispensable that one should enter into the utmost 

 topographical minutice. We shall not here, however, proceed to the ultimate 

 details of these organs, but merely place them in the proper light as far as their 

 site is concerned, and leave the rest to be worked out in the chapter (V) on the 

 anatomy of the various organs with which the body is diversified. 



50. TJie reproductive organs (?.-X^) would appear, Avithont mnch consideration, 

 to be as many as there are corners to the octagon which incloses them ; but we 

 are assured, for reasons which shall not be entered into here, but may be 

 found in the chapters on their anatomy (V) and on ordinal characters (XIII), 

 that there are only four subdivisions of this system, but that each part is two- 

 fold. The whole system is adherent to the inner surface of the anterior wall, 

 circumoral area, (Q of the umbella, and, from its proximo-distal extent, lies in 

 almost the closest possible contiguity to the proboscis. Each half of the four 

 subdivisions corresponds to one of the dark, triangular, pavement-like bodies already 

 referred to (44). The triangle (figs. 22, 37, ?}, X", >J) is broadly obtuse, and its 

 longest, basal side (X^) stretches in a slightly curved line, and at a very sharp 

 angle to the neighboring partition, from a point close to the bases of the tentacles, 

 two-thirds, or even three-quarters, of the distance (?„■* to X^) to the axis of the body. 

 Of the two other sides, one is shorter (P„") than the other (Z'), and lies nearer 

 the proboscis. They are both more or less outwardly arched, and by their 

 conjunction sometimes appear to form parts of a continuous curve rather than a 

 very obtuse angle. Each partition (>|-) lies midway between the two triangular 



