LUC E UN A lll^ AND THEIR ALLIES. 79 



Except in the case of 6*, 6 we do not know how the above enumerated rows 

 are extended on each side. It is plain that b", 6 extend row 3 on each side, since 

 they do not introduce a new row. Hence we infer that row 1 is extended by the 

 development of tlie tentacles on each side of No. 1 ; and so with row '2'\ 2, and ;i, 

 etc. etc. In Carduella it appears that row 1 is extended so as to have at least 

 half a dozen tentacles before row 2 begins, and that row 2 also extends consider- 

 ably before row 3 commences. In Uulimocijallms, the development is more rapid 

 in the formation of new rows, contrasted with the lateral extension of the oldest 

 rows in Haliclijsius, as we have shown in our Prodromus (Journ. Boston Soc. Nat. 

 Hist. 1863, p. 534). 



157. The proportions of length and thickness of the oldest tentacles have 

 changed considerably since the last phase, and they are much more slender in the 

 present case, but yet quite heavy when contrasted with those of the full-grown 

 animal. The prominence of the groups is due not alone to the lengtli of the ten- 

 tacles, but is increased considerably by the strong projection of the angles of the 

 umbella. Taking this into account, and also the fact that the marginal interval 

 between the groups and tlie anchors is much greater than in the last phase, we 

 can readily understand wliy tliese two sets of prehensile organs do not seem to form 

 a continuous row along the umbellar border. 



158. 71ie ancJioffi {Ji<j. 20, oc). The tentacular origin of these bodies is still 

 strongly hinted at, notwithstanding the greatly increased development of the colleto- 

 cystigerous mass. The latter, when seen from in front, forms a Y-shaped figure 

 about as long as wide, and bears the tentacle-like portion in the deep terminal sinus. 

 Altogether about one-half of wliat was originally a tentacle still retains that form, 

 while the basal lialf is disguised by the development of the colletocystigerous mass. 

 One-third only, or a little less, of the intertentacular umbellar margin is occupied by 

 the basal attachment of the anchor, leaving unoccupied, therefore, two-thirds of it as 

 a pure border, unmodified by the lateral extension of the neighboring organs. This 

 is, in a marked degree, a contrast with the corresponding space in the preovuline 

 stage (§ 20), when the transition from the bases of the tentacles to those of the 

 anchors was almost iniinterrupted by a margin. 



159. The general cavilij is but slightly modified since the last stage, and that 

 only in the nmbclla, where the incipient genitalia (X) form slightly raised, elon- 

 gate-oblong plateaus. Of course it will be understood that these plateaus are built 

 up, as it were, by the closely juxtaposed, nascent genital saccules, eventually con- 

 stituting a sort of pavement-work, as in the full-grown animal. The partitions 

 (4-^) are as yet quite thick, and very conspicuous from without. They seem to 

 have the full proximo-distal extent of those of the oldest individuals. Their 

 diameter is increased, no doubt, largely by the great depth of the ijastropJiragma 

 (^ 75, 76), which is nearly or altogether as thick in the peduncle and uiubrlla as 

 at the bases of the tentacles or within them. The actual thickness of the gastro- 

 phragma is much greater in the umbella and peduncle than at the same points in 

 full-grown bodies. The four camera; (.A','7. 127, t^) of the peduncle, as yet, remain 

 totally distinct from each other posteriorly. They lie nnich nearer the axis (^fi<J. 

 128), and occupy a larger portion of the peduncle than in their maturity, by one- 



