ulrich-bassler] revision of paleozoic bryozoa 281 



factors, and cause its reference to the Ascodictyonidce. On further 

 reflection, however, the absence of the dehcate threads which connect 

 the ckistered or isolated vesicles in Ascodictyon appeared a more im- 

 portant factor and induced us to classify the genus with the VincUidce. 



ALLONEMA BOTELLOIDES new species 

 (Plate LXVII, 2-4) 



In this species the internodes form strings of oblong, usually short, 

 sausage-shaped links, averaging about 0.5 mm. in length and varying 

 little from 0.25 mm. in width. In a colony holding this average, 

 many of the links may be merely a little constricted or cjuite divided 

 about the mid-length, while others may not be clearly divided from 

 the next following links. Others again, especially where the links 

 are crowded, will be abnormally narrow. Still, these variations do 

 not seriously affect the general average of size and form of the inter- 

 nodes, nor the general aspect of the colony that is sufficiently charac- 

 teristic to enable the observer to recognize the species at a glance. 

 Traces of the surface puncture are nearly always preserved, but the 

 larger zooecial pore is not so often seen. In excellently preserved 

 examples, less than half of the internodes exhibit evidence of having 

 supported zooecia. 



Colonies of this species vary from a few internodes to others 

 spreading over a space an inch or more across. They are readily dis- 

 tinguished from the associated A. hoteUus (Vine) by their more 

 robust aspect, and proportionately shorter internodes. 



Occurrence. — Common on corals in the Silurian of the Island of 

 Gotland. 



Cat. No. 43,126, U. S. N. M. 



ALLONEMA BOTELLUS (Vine) 



(Plate LXVII, i) 

 1884. Rhopalonaria botcllits Vine, Ann. & Mag. Nat. Hist., ser. 5, vol. 

 XIV, p. 85, fig. iv, 3; 1887, Proc. Yorkshire Geol. & Polyt. Soc, vol. 

 IX, p. 185; pi. 12, figs. II (?I2). 



This species is associated with the genotype in the Silurian rocks 

 of Gotland, and the two forms not infrequently occur on the same 

 coral or shell. We have, however, experienced no serious difficulty 

 in distinguishing them, A^ine's species having always a decidedly more 

 delicate aspect. The average lengths of the internodes is about the 

 same in both, but on account of their lesser width in A. hotel I us, in 

 which this dimension usually varies between o.i mm. and 1.15 mm., 

 they are proportionately more elongate than in our A. boteUoides. 



