REPORT OF THE STATE PALEONTOLOGIST 1901 577 



Thecae. From this sicula buds at first, close to its distal end, 

 one theca (1), which for a short distance grows in a distal direc- 

 tion along the sicula, then, turning abruptly under an approxi- 

 mately right angle, follows a horizontal or slightly downward 

 direction (assuming the suspended position of the colony). (See 

 fig. 1 and 3) The apparent angle of its divergence changes 

 slightly, as is illustrated by fig. 2 and 3. From theca 1 is pro- 

 duced again by gemmation and close to its proximal end theca 



Fig. 1 Gonio- 

 graptus thu- 



reaui McCoj-. Fig- 2 Idem^ Sie- 



var. postre- ula (from antisicular 



mus. Sicula side) ; and branches pj 3 ^^g,^ game, 



and first two of first and second or- from sicular side. x3^ 



thecae (fun- der. x3}^ 



icle). x3>^ 



2, which, growing across the " antisicular " side of the sicula, 

 diverges to the opposite side under exactly the same angle as 

 theca 1. In older colonies the thick, straight, uninterrupted 

 cross bar between the principal branches has been termed, in 

 other multiramose dichograptids, the " funicle " by Hall and 

 succeeding authors on graptolites. As the somewhat larger 

 colonies usually settle on their broader surfaces, the sicula is 

 brought into a vertical position, and hence often fails of observa- 

 tion in the fossilized state, as in fig. 4, where the central thick- 

 ening indicates its location. 



Each of these primary thecae produces in its turn (fig. 3), in 

 a like position and manner as the sicula did, a new theca, which 

 also, after a short adherence to the mother theca, turns aside 

 at the same angle as does theca 1 and, like the latter, sends a 

 new theca, corresponding to theca 2, to the opposite side. The 

 bifurcation near the aperture of the sicula of the first two 

 thecae is hence repeated at the aperture of each of the latter, 

 and four secondary thecae result. These four thecae form the 

 four " primary branches " of other authors. Each of these pro- 

 duces a new bifurcation (fig. o and 6) by the same process 

 of twice repeated gemmation in two succeeding thecae, and the 



