MORPHOLOGY OF UROHYAL BONES OF PLEURONECTIDAE FISHES IN KOREAN WATERS

한국산 가자미과 어류의 미설골의 형태에 관하여

The present paper deals with the results of the comparative morphology on the urohyal bones on the right-eye flounders, pleuronectidae fishes in Korean waters. The results obtained are as follows : 1. The position of the tip of sciatic part is quite different depending on the genera and species of the fishes. The sciatic part of the genera, Platichthys and Cleisthenes, is very short extending to the middle portion of the main part. In the fishes of Eopsetta and Tanakius, it is also very short extending to the anterior 1/3 of the distance from the tip of main part. The fishes of Verasper and Dexistes have a short sciatic part which extends toward the posterior 1/4 of the distance from the tip of main part. The fishes Of Limanda, Clidoderma, Glyptecephalus and Microstomus have a long sciatic part which extends as long as the main part. However, those of Kareius and Pleuronichthys have a very long sciatic part extending twice long as the main part. The tip of sciatic part of the fishes belonging to Eopsetta, Verasper, Limanda, Platichthys, Tanakius and Glyptocephalus is a truncate form. It is pointed upward in the fishes of Kareius, Pleuronichthys, Clidoderma and Microstomus, but pointed forward in Cleisthenes and Dexistes. 2. The size and form of the cardiac apophysis vary with the developmental grades of the urohyal bone. The fishes of Eopsetta, Verasper, Platichthys, Tanakius, Kareius and Dexistes possess relatively large apophyses and those of Pleuronichthys and Clidoderma have small apophyses. Intermediate size of the apophysis is found in the fishes of Limanda, Microstomus and Cleisthenes. A long and barlike apophysis is found in Glyptocephalus. Three kinds of the cardiac. apophysis are found in the fishes examined, i. e., lateral wing in Eopsette, Verasper, Limanda, Platichthys, Tanakius, Glyptocephalus, Kareius, Pleuronichthys and Clidoderma, pointed forward in Microstomus and Cleisthenes, and truncate with a well-developed inner ridge type in Dexistes. 3. The angle of the main part and sciatic part varies from 30 to 60 degrees in the fishes studied except for the fishes of Pleuronichthys, Clidoderma and Microstomus which show a semi-elliptical form.

한국산 가자미과어류의 미설골의 형태를 비교 관찰하여 다음과 같은 특질을 가지고 있음을 알았다. 1. 좌골부선단의 위치가 속 또는 종에 따라 달리하고 있는데, 주부의 선단에서 각을 이루는 부분까지의 거리의 1/2(Platichthys 및 Cleisthenes), 앞쪽에서 1/3(Eopsetta 및 Tanakius), 뒷쪽에서 1/4(Verasper 및 Dexistes), 동일위치 (Limanda, Clidoderma, Glyptocephalus 및 Microstomus), 2배의 거리 (Kareius 및 Pleuronichthys)에 있는 것등으로 나누어지며 , 좌골부선단의 모양은 절두형인 것(Eopsetta, Verasper, Limanda, Platichthys, Tanakius 및 Glyptocephalus), 끝이 뾰족하고 위로 향한 것(Kareius, Pleuronichthys, Clidoderma 및 Microstomus), 끝이 뾰족하며 앞으로 향한 것(Cleisthenes 및 Dexistes)등 세가지형으로 나누어진다. 2. 분문돌기는 발달정도에 따라 차이가 있고 그 모양도 다양하다. 비교적 큰 것에 속하는 것(Eopsetta, Verasper, Platichthys, Tanakius, Kareius 및 Dexistes), 작은 것(Pleuronichthys 및 Clidoderma), 막대기 모양인 것(Glyptocephalus), 보통인 것(Limanda, Microstomus 및 Cleisthenes)등 의 네가지로 나누어지며, 모양은 상연이 둘로 갈라져 날개 모양을 한 것(Eopsette, Verasper, Limanda, Platichthys, Tanakius, Glyptocephalus, Kareius, Pleuronichthys 및 Clidoderma), 끝이 뾰족한 것 (Microstomus 및 Cleisthenes), 절두형에다 내연이 발달한 것(Dexistes) 등 세가지로 나누어진다. 3. 주부와 좌골부가 만드는 각도는 Pleuronichthys, Clidoderma, Microstomus의 반타원형을 제외하고는 $30^{\circ}$에서 $60^{\circ}$까지의 각도를 이루고 있다.