LOCALIZED STAGES IN DEVELOPMENT. 135 



In the next septnni fignred (PL 25, fig. 119) the first sarlrlle is slightly twice den- 

 tate, comparatively complicated. (For brevity in comparison, the saddles and lobes are 

 numbered from 1 upward, instead of external saddle, first lateral saddle, etc., as is fre- 

 quent in descriptions.) Saddle 2, twice dentate, but simple'-. Saddle .3, deeply once 

 dentate, sinapler than 2. Saddle 4, once dentate. Saddle 5, once dentate, simpler than 

 saddle 4. Saddle 6, slightly bilobed. Saddles 7-11, entire, like all the saddles of Fig. 



118. Lobe 1 has two slight marginal saddles, simple. Lobes 2-4 have each one mar- 

 ginal saddle, progressively decreasing toward the umbilicus. Lobes 5 and 6 have no 

 marginal saddles and are simpler tlian lobes 3-4. Lobes 7-11 are entire, comparable to 

 all the lobes of Fig. 118. 



h\ tlie third septum figured (PI. 25, fig. 120), saddle 1 is twice dentate, the most 

 complex saddle of the septum. Saddles 2-3 are slightly twice dentate, comparable to 

 but more complex than saddle 1 of Fig. 119. Saddle 4 is very slightly twice dentate, 

 comparable to but more complex than saddle 2 of Fig. 119. Saddles 5-7 are distally 

 bilobed, otherwise slightly dentate, comparable to saddles 3-4 of Fig. 119. Saddle 8 is 

 bifid, slightly dentate, comparable to saddle 5 of Fig. 119. Saddle 9 is slightly indented, 

 comparable to saddle 6 of Fig. 119. Saddles 10-11 are entire, comparable to saddles 

 7-11 of Fig. 119 and all the saddles of Fig. 118. Lobe 1 is uneven in outline, but has 

 two prominences whicli may apparently be compared to the marginal saddles of lobe 

 1, Fig. 119. Lobe 2 is irregular, but has two marginal saddles, both slightly dentate. 

 Lobe 3 has one marginal saddle, dentate, and two very slight saddles entire. These 

 entire marginal saddles are comparable to the entire marginal saddles of lobes 1-3, Fig. 



119. Lobes 4-8 have slight marginal saddles, comparable to lobes 2-4 of Fig. 119. 

 Lobe 9 has no marginal saddle and is comparable to lobe 5 of Fig. 119. Lobes 10-11 

 are entire and are comparable to lobes 7-11 of Fig. 119 and all the lobes of Fig. 118. 



The fourth septum figured (PI. 25, fig. 121) is the most complicated of this series. 

 Saddle 1 is deeply twice dentate, the most complex of the septum and more complex 

 than any saddle of Fig. 120. Saddles 2-4 are twice dentate, and comparable to saddle 1 

 of Fig. 120. Saddles 5-6 are slightly twice dentate and comparable in general to 

 saddles 2-3 of Fig. 120. Saddles 7-S are lobose, dentate, comparable to saddle 4 of 

 Fig. 120. Saddles 9-10 are bifid, slightly dentate, comparable to saddles 7-8 of Fig. 



120. Saddle 11 is entire, comparable to saddles 10-11 of Fig. 120, saddles 7-11 of Fig. 

 119, and all the saddles of Fig. 118. Lobe 1 has several dentate marginal saddles more 

 than other lobes of its own or preceding septa. Lobes 2-4 have fewer marginal sad- 

 dles and are generally simpler than lobe 1. Lobe 5 has a simple saddle, and one slightly 

 dentate marginal saddle, comparable to lobe 3 of Fig. 120. Lobes 6-8 have simple 

 marginal saddles, comparable to lobes 5-7 of Fig. 120. Lobes 9-11 have no marginal 



