486 University of California Publications in Zoology [Vol. 16 



The data contained in the above table are presented as a little 

 study on the problem of variation of organisms produced monogenet- 

 ieally. The two facts revealed by them are sufficiently significant to 

 warrant their publication, indicating as they do the desirability of sub- 

 jecting the point to a special investigation. First there is a consider- 

 able range of variation among the zooids in a colony, the extremes 

 being 16 and 23 in colony number 2. This result is not in harmony 

 with the widely held notion that variation does not take place to any 

 extent among individuals produced asexually from the same parent. 

 The second notable fact is that some of the colonies, especially number 

 4, have a very distinct mode of their own. The question as to whether 

 we have here a case of what may be called somatic heredity obtrudes 

 itself and invites experimental study. 



Amaroucium solidum, n. sp. 



PI. 46, figs. 69 and 70 



Superficial characteristics of the colony. — Large, fleshy, potato- 

 shaped lobes ; j'oung colonies more globular ; largest colony studied, 

 length 16 cm., width 7 cm., thickness 3.5 cm. Some living colonies 

 opalescent white, the zooids showing as opaque white objects; others 

 opalescent with a .yellowish blue tinge, the zooids distinctly yellow. 

 Zooids very numerous, standing at various angles in colony. Systems 

 seemingly never pre.sent. Test gelatinous with many variously shaped 

 pigment grains ; surface layer tougher than underying portion. 



Zooicls.^A little pressure on a living colony forces zooids out upon 

 surface ; easily removed from test in preserved specimens ; varying 

 greatly in length, some very long, extending well back into central 

 gelatinous core ; average length in large colony, thorax 3 mm., 

 abdomen 2 mm., postabdomen 8 mm. Mantle delicate and transparent, 

 containing about twenty-four longitudinal muscle bands on a side, 

 these separated by considerable spaces in the thorax but closer together 

 in the abdomen and postabdomen ; a few transverse fibers in the 

 siphonal region. 



Branchial system. — Branchial siphon with six blunt lobes grooved 

 so as to appear twelve when viewed from above ; atrial siphon with 

 -short, overhanging, triangular languet and five small, pointed lobes. 

 Branchial sac with from thirteen to fifteen series of stigmata, each 

 series having about fifteen stigmata on a side in middle of sac (pi. 46, 

 fig. 69). Endostyle wide and straight, with a narrow space on each 

 side free from stigmata. Branchial tentacles about twenty, of varying 

 sizes. 



Digestive system. — Plane of intestinal loop, transverse ; esophagus 

 almost as long as stomach ; stomach cylindrical, one and one-half times 

 longer than wide, having about eight folds, these sometimes discon- 

 tinuous (s.. fig. 69) ; intestine divided into several parts (pi. 46, fig. 

 70) ; first, a piece a little shorter than stomach with a bulge about mid- 



