MUSEUM OF COMPAKATIVE ZOOLOGY. 41 



in counection with the species which I have used in common with them, 

 or in the general part of this paper, in considering the process of budding 

 in Bryozoa as a whole. 



I will begin my description with Bugula turrita ^ of Verrill, which I 

 gathered in the summer of 1889 at Wood's Holl, where it occurs abun- 

 dantly on the piles of the wharf. The stock is bushy, and, when its 

 polypides are active, of an orange color. In its simplest form the 

 stock consists of a central axis, which is somewhat zigzag, and gives off 

 lateral branches like the trunk of a tree. The lateral branches are in- 

 serted on the trunk in a spiral line. Each lateral branch is ftin-shaped 

 (Plate VII. Fig. 64), the part corresponding to the handle of the fan 

 being the point of attachment, and the fens are smaller the nearer they 

 are to the tip of the trunk. The attachment of the branch to the 

 trunk is effected by one primary individual. Each fan-shaped branch 

 extends from its point of attachment obliquely upward and outward, 

 and, although it is slightly concave on its upper inner surface, the 

 concavity is not sufficient to prevent its being spread out upon the slide 

 for study without materially disturbing the interrelation of the indi- 

 viduals in the stock. 



I have studied several branches flattened in this way (one of 400 

 individuals), and have made camera drawings of them. Since the 

 results in the different cases are substantially in agreement, I have con- 

 cluded that they are significant. One of these camera drawings is shown 

 in the figure just referred to. 



To designate individuals in the stock, I have adopted a simple no- 

 menclature. The forty-four terminal individuals are numbered from 

 1 to 44. The successive generations (if I may be allowed to use this 

 word in a loose way) are indicated by the Roman numerals from I. to 

 XIII. A.ny one individual is indicated by placing the numbers of the 

 radial line or lines to which it belongs first, and following this by 

 the Roman numeral of the generation to which it oelongs. Thus, 

 27-30 IV. is an individual near the base of the twig 27-30 and of 

 generation IV. Figure 64^ (Plate VII.) is a diagram showing the 



1 This species is very similar in general habit to B. avicularia, Linnaeus, and to 

 B. turbinata, Alder (Hincks, '80, pp. 75-80). It differs from the first named spe- 

 cies by possessing only one spine, on the outer upper edge, as described by Leidy 

 ('55, p. 142), instead of having three, — two outer upper and one inner and upper. 

 It differs from Hincks's diagnosis of the second in having only two " cells " in each 

 branch, instead of 3-6 in the upper portions. The form of the aviculariura would 

 seem to ally it more closely to B. avicularia. 



