HEAD SOMITES AND EYE MUSCLES IN CHELYDRA 



165 



ABBREVIATIONS 



aud., ear 



ac. X, vagus accessory nerve 



hr., brain 



Ch., notochord 



cil. g., ciliary ganglion 



con. St., connecting-stalk of first head 

 somites 



div., diverticulum from ventro-lateral 

 wall of first head somite 



ec, ectoderm 



/. ac, facio-acustic ganglion 



F. B., forebrain 



fg., foregut 



H. B., hindbrain 



hyo. cl., hyomandibular cleft 



inf. + med. recti, inferior and medial 

 recti muscles or their anlages 



I., lens 



I. r., long root of ciliary ganglion 



Man. v., mh. n. mandibular ramus of 

 N. trigeminus 



Max. v., maxillary ramus of N. tri- 

 geminus 



max.-man., maxillo-mandibular muscu- 

 lature 



mes., disintegrating portion of wall 

 of first head somite 



mus. 2, mus. 3, muscle anlages of gill 

 arches 



n. abd. 2, abducent branch to muscu- 



lus rectus lateralis 



N. abd.,\ , , 



,. ^rT r nervus abducens 



na. cil., nasociliary branch of nervus 

 trigeminus 



nervus oculomotorius 



n.oc, 1,2, branches of nervus oculomo- 

 torius to eye muscles 



N. oc, 



N. Ill, 



N. troc, nervus trochlearis 



ohl. inf., musculus obliquus inferior 



ohl. sup., musculus obliquus superior 



op. c, optic cup 



op. St., optic stalk 



Ophth. art., ophthalmic artery 



Ophth. V, ophthalmic division of N. 

 trigeminus 



pre., prechordal plate 



red. lat., musculus rectus lateralis • 



rect. inf., musculus rectus inferior 



rect. med., musculus rectus medialis 



rect. sup., musculus rectus superior 



retr. oc, musculus retractor oculi 



Si, S2, S3, first, second and third head 

 somites 



S.C.N., short ciliary nerves 



St., in model, remains of connecting- 

 stalk of first head somite 



tri., nervus trigeminus 



tri. g., trigeminal ganglion 



X., ventral cell-mass of second head 

 somite 



z, cell-mass of doubtful significance 

 and derivation. 



V 2 -\- 3, maxillo-mandibular trunk of 

 N. trigeminus 



VII, nervus facialis 



IX, nervus glossopharyngeus 



X, nervus vagus 



