OPHTHALMIC NERVES OF GNATHOSTOME FISHES 75 



In Lepidosteus, van Wijhe ('82) describes both a ramus oph- 

 thalmicus profundus trigemini and a ramus ophthalmicus super- 

 ficialis trigemini. In a 75-mm. specimen of this fish I find the 

 so-called ophthalmicus superficialis trigemini composed of later- 

 alis, communis and general cutaneous fibers, the lateralis fibers 

 forming a bundle which lies somewhat above the communis and 

 general cutaneous ones. A radix profundi arises from the me- 

 dulla anterior, and close to the general cutaneous root of the tri- 

 geminus, and issues from the cranial cavity by an independent 

 foramen. A profundus ganglion forms on this root, and from it 

 a radix longa, a ramus ciliaris longa, and a portio ophthalmici 

 profundi arise. There is no perceptible trace of a ramus oph- 

 thalmicus profundus. The portio ophthalmici profundi runs 

 upward and joins and fuses with the communis and general cu- 

 taneous components of the ophthalmicus superficialis, as shown 

 but not index-lettered in Luther's figure of this fish ('13, fig. 1) , but 

 as there is no pedicel to the alisphenoid of this fish (Allis, '09) the 

 relations of the nerve to that element of the skull are, as in Polyp- 

 terus, undefined. The conditions in this embryo thus show that 

 the so-called nervus ophthalmicus profundus of Landacre's ('12) 

 descriptions of a 10-mm. embryo of this fish is probably a portio 

 ophthalmici profundi and not a ramus profundus ; and this nerve 

 accordingly cannot be, as Landacre concludes in a later work 

 ('16, p. 27), a nerve comparable to the ramus ophthalmicus pro- 

 fundus of the Selachii. 



In Acipenser' van Wijhe ('82) describes a so-called ophthalmi- 

 cus profundus trigemini, but as this nerve is said to run forward 

 dorsal to all the muscles of the eyeball, and is shown in his figure 

 lying dorsal to the nervus trochlearis, it must be either a portio 

 ophthalmici profundi, a ramus ophthalmicus superficialis tri- 

 gemini, or both those nerves combined. WTiich one it is cannot 

 be told either from his descriptions or from those of Gorono- 

 witsch ('83), for the profundus ganglion is completely fused with 

 the trigeminus ganglion. 



In a 40-mm. specimen of Gasterosteus acus, in which fish there 

 is an anterior portion of the ascending process of the parasphenoid 

 that replaces the pedicel of the alisphenoid (Allis, in press), the 



