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664 R. C. PUNXETT.— '^^S*-!^^- Mean for Group 1 = 4-94 38Collar lengthNo. of Specimens„ „ „ 2 = 4-90 33„ „ „ 3 = 4-84 15Average 4'90Totan^|^_ Mean for Group 1 = 23-1 19Collarlength„ „ „ 2 = 22-4 17„ „ „ 3 = 23-4 13Average 22-9An examination of the above table brings out clearly the important fact that two ofthe three ratios, i.e. those of the genito-hepatic and total lengths, are quite unaffected bygrowth changes, whilst that of the branchial region is not greatly affected. Neglectinggroup 4 in which there are so few specimens there is a gradual rise in the ratio withincrease in size from 2*08 in group 1 to 2-18 in group 2, and 2-36 in gi-oup 3. There istherefore an increase of about 12 7o in group 3 as compared with group 1, an increasesufficiently well-marked though not very great when we take into account the unavoidableroughness of the measurements. A possible source of error must be noticed here. A considerablenumber of specimens (some 8—10 7o) were regenerating. Where this process wasobviously at work the specimens were not included in the above measurements. In thelatest stages, however, regenerated individuals are impossible to distinguish from ordinaryones with a somewhat shorter branchial region than usual. As regeneration is far morecommon in the smaller specimens it seems almost certain that the values of the ratio forgroups 1 and 2 are somewhat too low in comparison with those of gi-oup 3. On the wholeit would appear from these measurements on laccadivensis that the proportions of the bodyof this Enteropneust are very little, if at all, liable to alteration during the later stagesofgrowth.This conclusion is borne out by a similar series of measiirements made on Pt. Jiava,var. maldivensis. The 52 specimens of this variety were divided into three groups of whichthe last contained only the five largest specimens (see Table 13, p. 674). On taking themean for the three ratios in each group the following figures were obtained.Branchial lengthCollar lengthGenito-hepatic lengthyCollar lengthTotal lengthCollar lengthTable 7.No. of Specimens^ean for Group 1 = 1-65 19„ „ „ 2 = 1-62 28„ „ „ 3 = 2-00 5Average 1-67^^^^^^ ^^^ ^ ^ ^.^^ jg„ „ „ 2 = 4-14 28„ „ „ 3 = 5'23 5Average 4 -41Mean for Group 1 = 16-5 6„ „ „ 2 = 18-7 9„ „ „ 3 = 17-6 2Average 17-7