The present paper, the sixth o f the series of the pelagic fish eggs from Japanese waters, contains the figures and descriptions of the egg development and hatched larvae of 22 species as well as early embryonic development of a single species, Cirrhilabrus temmincki Bleeker, belonging to the suborder Labrina. The eggs of this suborder, excepting ellipsoidal egg of Callyodon ovifrons (Temminck et Schlegel), are globular in shape, 0.5-1.1 mm in diameter, containing a single colorless or yellow oil globule measuring 0.07-0.21 mm in diameter. The egg membrane is smooth, without any conspicuous structure, the yolk not segmented, the perivitelline space narrow. During the course of the egg and larval development only the melanophores appear. The newly hatched larvae have ovoid yolk sac which is usually protruding anteriorly beyond the head, and the oil globule is situated in the anterior part of the yolk. The number of myotomes of the hatched larva is about 27. The location of the melanophores of the hatched larva changes greatly during the larval development. Soon after hatching, serration appears in many species on the fringe of the marginal fin. The eggs belonging to Labrina can be divided into 4 groups according to the situation of the melanophores at hatching, and the species belonging to each groups of 1-4 are as follows : 1. No pigment-cell developed in the egg......Labrina Nos. 1-3. 2. Melanophores are seen only on the body......Pseudolabrus japonicus (IIouttuyn), Halichoeres poecilopterus (Temminck et Schlegel) and Labrina No. 4. 3. Melanoph o res are seen on the body as well as on the oil globule ; the melanophores on the dorsal median line of the body arranged in a sing l e row......Stethojulis kalosoma (Bleeker), Thalassoma cupido (Temmincket Schlegel), Leptoscarus japonicus (Cuvier et Velenciennes) and Labrina No. 5-9. 4. Resembling to the previous group, but the melanophores on the dorsal median line of the body arranged in two or more rows......Duymaeria flagellifera (Cuvier et Valenciennes), Halichoeres tenui spinnis (Gunther), Callyodon ovifrons and Labrina Nos. 10-14. The egg of C. ovifrons is ellipsoidal in shape measuring 1.31-1.66 × 0.50-0.61 mm in diameter, having a single oil globule measuring 0.15-0.17 mm in diameter. Other features of the egg, egg development and hatched larva are much the same as those of other labrid fishes. As Winn and Bardach (1960 ) has pointed out the shape of the egg belonging to the family Scaridae, one of the two families of Labrina, is globular or ellipsoidal. It seemed that the egg is globular in the species belonging to the subfamily Sparisominae and ellipsoidal in the subfamily Callyodontinae.
この報告ではべラ亜目Labrinaに属する23種の卵,卵内発生および孵化仔魚について述べる.これらのうちの数種については,その卵内発生および孵化仔魚の性質がすでに判明している.現在までに我国から知られているベラ亜目の魚卵我は径0.5~1.1mmの球形分離浮游性卵で,卵膜および卵黄には特殊な構造はなく,卵膜腔は狭い.油球は1個,無色のものから黄色のものまであるが,Bolin(1930),Orton(1955)等も述べているように,卵内発生中に槌色するものが多い.この亜目はべラ科Labridaeとブダイ科Scaridaeの2つの科を含むが,卵の性質,卵内発生および孵化仔魚の観察からは両者を識別することは困難であつた.しかし,最近の研究からブダイ科の魚のうちアオブダイ亜科Callyodontinaeに属するものは楕円形の浮性卵を産むらしいことが分つた(Winn and Bardach,1960).なお外国産の種類では沈性粘着卵や油球を欠く浮性卵を産むものが知られているが,このような卵を産む種類は我国からは未だ知られていない.ベラ亜目の卵は卵内発生中に全く色素胞が現われないか,胚体上または胚体および油球上に黒色素胞のみが現われる.孵化仔魚の卵黄は体の腹面に細長く着生し,その前端は頭部より前方に突出し,油球はその突出部にある.肛門は卵黄からやや離れ,体の中央より後方に位置する.筋肉節数は27前後.後少時を経ると膜鰭縁辺に針状構造物が現われるものが多い.黒色素胞は,多くの種類では,時孵化間の経過に伴つて体の背面にあつたものが腹面へ移動する.この黒色素胞の位置の移動と集散は著しく,卵黄を吸収し尽す頃にはその種固有の位置を占めるようになる.この報告ではべラ亜目の魚卵のうち,ベラ科とブダイ亜科Sparisominaeに属すると思われるものを一括してベラ類と呼び,それらを黒色素胞の出現状態によつて次の4群に分けた.第1群.卵内発生中に黒色素胞が現われない.第2群.卵内発生中に胚体上にだけ黒色素胞が現われる.第3群.卵内発生中に胚体および油球上に黒色素胞が現われる.孵化直後の仔魚の体の背面の黒色素胞は背中線上に1列に並ぶ,第4群.第3群と同様であるが,孵化直後の仔魚の体の背面の黒色素胞列は2列またはそれ以上.にこれら各群に属する種類について述べるが,その前に卵内発生と孵化仔魚の概要を人工以授下精を行なつたカミナリベラについて述べる.