120 



GEODIA AGASSIZII. 



DIMENSIONS OF LARGE CHOANOSOMAL AMPHIOXES OF GEODIA AGASSIZII.' 



Station 



2886 



2887 



2978 



3088 



3168 



4193 



4199 



4228 



4551 



All Sta- 

 tions 



4228 



Length 



of apparently 

 full-grown spic- 

 ules, mm. 



2 4- 

 3.8 



2 . 4- 

 4.1 



3 5- 

 4,2 



3 5- 

 4.4 



3 1- 

 4.5 



3 1- 

 4.8 



2 4- 

 3.9 



*i . o— 



3.5 



9 7 



4 



9 Q 



z . o— 

 4.8 



O 1 

 Z . 1— 



3.4 



average of the 

 three longest, 

 mm. 



3 4 



3.8 





4 









O . Z 



*? c 

 o . o 



Q O 



o . y 



O . 1 



Thick- 

 ness 



of apparently 

 full-grown spic- 

 ules, 



60- 

 81 



80- 

 100 



90- 

 112 



65- 

 82 



80- 

 93 



72- 

 95 



64- 

 85 



35- 

 80 



68- 

 100 



60- 

 112 



20- 

 66 



average of the 

 three thickest, ji 



75 



93 



111 



76 



89 



87 



79 



74 



93 



86.3 



57 



The large, thick, club-shaped styles (Plate 28, figs. 12-14), which occur in 

 small numbers in the specimens from Stations 3168 and 4193, are straight or 

 slightly curved, always thickened at the rounded end, and 115-145 pt thick. 



The minute dermal amphioxes (Plate 27, figs. 3a, 7a, 8a) occur in all speci- 

 mens. They are slightly curved and usually not very sharply pointed at the 

 ends. Sometimes one end is much more blunt than the other, but the bluntness 

 never seems to be great enough to make the spicule appear as a style. In the 

 adult specimens these spicules are 160-480 //long and 5-12 //thick, their average 

 maximum dimensions being 342 X 9.06 fi. Those of the specimens from Station 

 2886 are considerably larger, both longer and thicker, than those of the others. 

 Particularly slender ones are met with in the adult specimen from Station 4228. 

 In the young specimen from Station 4228 these spicules are 225-300 /i long 

 and 4-7 /« thick. In the immature specimen described by Lambe they are 180- 

 480 by 3-8 /(. 



DIMENSIONS OF SMALL DERMAL AMPHIOXES OF GEODIA AGASSIZII. 



station 



2886 



2887 



2978 



3088 



3168 



4193 



4199 



4228 



4551 



From all Stations 



4228 





Length, /i 



220- 

 480 



210- 

 340 



230- 

 270 



260- 

 360 



160- 

 290 



270- 

 390 



290 



185- 

 330 



310- 

 330 



160-480 

 maximum aver- 

 age 342 



22.5- 

 300 



Thickness, /i 



7-12 



8-10 



7-8 



8-10 



7 



7-10 



8 



5-8.5 



8 



5-12 

 maximum aver- 

 age 9.06 



4-7 



1 In this and the following tables the specimen from Station 4228 is a young specimen; those from the other 

 stations are adults. 



