NO. 3593 VICTORELLA — BANTA 13 



waters. The marine species V. sibogae Harmer (1915) has been re- 

 moved by Braem (1939, p. 178) to a new genus, Sinulanella, on 

 anatomical grounds; Marcus (1941) agrees. The other morphological 

 characters of specific value depend on whether or not the animal is 

 in the A or B form. 



A number of explanations have been given for the great variations of 

 zoecial form in Victorella. In general, those authors who consider 

 V. miilleri synonymous with V. pavida have offered two explanations 

 for variation in zoecial length: the age of the zoecium and CTO'\\d- 

 ing of the colony. Most of these authors (Ulrich, 1926; Annandale, 

 1912; Borg, 1930; Braem, 1911; Soule, 1957; and Carrada and Sacchi, 

 1964) are of the opinion the V. miilleri is a juvenile form of V. imvida. 

 The best presentation is that of Ulrich (1926). Valkanov (1943, p. 5), 

 on the other hand, seems con\dnced that zoecial crowding caused by 

 local irregularities of the substrate induces a lengthening of the 

 zoecium, presumably by restricting growth laterally. More recently 

 Brattstrom (1954, p. 11) stated: "It is possible that the two species 

 here treated (if really separate) are capable of great seasonal variations 

 as well as of variations resulting from environmental influences 

 (temperature, density of colonies, etc.) and thus, though anatomically 

 different, being able to appear in different growth forms ->A'hich are more 

 or less alike in the two species." 



In the case of V. argilla, the elongate B zooids are produced in two 

 possible ways: (1) by the elongation of the apertural papilla vertically 

 from the substrate and the degeneration of several successive poly- 

 pides, as described on page 8 (in this case, it is true that variability 

 is age-induced and that A colonies invariably produce B colonies, but 

 it should be noted that the zoecial wall of the B form represents the 

 apertural papilla of the A form) ; (2) by the budding of B zooids. As 

 mentioned before (p. 7), new buds may be formed as evaginations of 

 the body wall of the upright portion of the zoecium; such buds produce 

 only B zooids. Conversely, however, only A zooids are ever produced 

 by the "stolonal" budding of another A zooid (see p. 7). This 

 peculiar state of affairs may represent some biochemical difference 

 in the two kinds of buds but it could as easily be due to some more 

 direct physical influences. The zoecia may be so crowded, for in- 

 stance, that only vertical growth is possible, or perhaps the volume ol 

 B zooids is too great for the quantity of foodstufi's that can be trans- 

 mitted to the bud from feeding autozoecia through the connecting 

 tubules. In this case, perhaps only the efforts of several generations 

 of polypides within the same zoecium is enough to provide the 

 nourishment necessary to produce the large B zooids. It should be 

 recalled that some of these zooids may approach a centimeter in 

 length (see p. 7). 



