612 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



nerve threads in either plexus always appear smooth, showing no 

 swellings of any kind. Figure 34 (PI. 6) shows at c (near the upper 

 margin of the figure) a cell which is apparently associated with a 

 fine nerve plexus. 



These plexuses were found in nearly all specimens, of both species, 

 impregnated in the manner previously described. The specimens 

 retaining considerable epithelium were quite unfavorable for study; 

 on the other hand, with the sloughing off of the epithelium, portions of 

 the superficial plexuses were undoubtedly lost. A record, given below, 

 was made of the occurrence of these plexuses, indicating the species, 

 the side of the body, and the number of the nerve with wliich they were 

 associated. In nearly every case, portions of both the coarser and 

 the finer plexus were present. 



1. 

 2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 

 10. 

 11. 

 12. 

 13. 

 14. 

 15. 

 16. 



Species. Side of Body. 



B. lanceolatum left 



right 



left 



right 



left 



right 



B. caribaeum 

 B. lanceolatum 



B. caribaeum 

 B. lanceolatum 



left 



right 



left 



right 



Number of Xerve. 

 IX 



"<( ' \( [-same individual 



XV, XVI, XMI 



XXI, XXII ) .,..,, 



XXVT XXVTT \ s^^^^ mdividual 



xxvii 



XXIX, XXX 



XXXII 



XXXV, XXXVI, XXXVII 



ii it ii 



XXXVII, XXXVIII 

 XLI, XLII, XLIII, XLIV 

 XLII, XLIII, XLIV 

 XLVI, XLVII, XLVIII 

 LIV, LV 



LIII, LIV, LV, LVI, LVII 

 LIV, hX, LVI 



It is evident from this record, that these plexuses cannot be looked 

 upon as localized structures, or of infrequent occurrence. The record 

 shows no plexuses (those of the mouth border are not included) in the 

 rostrum, buccal region, or at the extreme posterior end of the animal. 

 This may be due to lack of impregnation, or these regions may show 

 differences in this respect. Figures 34, 35, 36 (PI. 6) and 38, 39, 41 

 (PI. 7) present the first published views of such cutaneous plexuses 

 distributed over the side muscles, either in situ or otherwise. 



