1889.] ANATOMY OF GONATUS FABRICII. 125 



nearly that of Ommastrephes, of all those which have hitherto been 

 described in detail \ The brachial ganglion {br.g.), however, is not 

 quite so widely separated from the pedo-visceral {p.v.) as in that 

 genus. 



The fusion between the pedal and visceral ganglia is very complete. 

 Buccal ganglia (h.g.) are situated upon the posterior extremity of 

 the buccal mass, and are connected as usual both with the cerebral 

 and brachial ganglia. Furthermore tliere is present a cerebro-bra- 

 cbial connective. 



The Peripheral nerves could scarcely be made out at all owing to 

 the disintegrated condition of the specimens, but it was easy to see 

 that the brachial commissure is simple as in all Decapoda. 



The Stellate ganglia are large flattened pyriform bodies ; they are 

 connected by a strong and easily recognized commissure. The pal- 

 lial nerve {p.n.) divides a httle distance before reaching the ganglion, 

 the main trunk passing directly backwards and reuniting with the 

 nerve given off from the posterior extremity of the ganglion. This 

 arrangement resembles in its general features that figured by Brock ^ 

 for Ommastrej)hes and Todarodes, but with certain minute differences. 



A number of sections were made of the Eije, but they did not 

 exhibit any features calling for special notice. 



The Osphradium consists of a small antero-posteriorly directed 

 ridge, which is placed below and a little behind each eye ; it could 

 be very clearly followed through a number of sections extending 

 perhaps over half a millimetre of the animal's length. The prepara- 

 tions did not show any of the histological features characteristic of 

 the osphradium, but I feel justified in regarding this ridge as such 

 partly because of its position, and partly because just internal to 

 each of these ridges there was a foramen in the cephalic cartilage 

 through which passed a nerve. 



The Auditory Organs occupy their usual position. 



VII. Digestive Organs. 



The Beak is remarkable chiefly for the long curved apex of the 

 superior mandible. It has been figured by Steenstrup, but unfor- 

 tunately the plate containing it has not yet been published. 



The Radula has been admirably figured by Sars ". It is remark- 

 able as being the only known Cephalopod radula in which only five 

 rows of teeth are present. On comparing it with the radulee of 

 Onychoteuthis * and Enoploteuthis " it appears that the teeth which 

 have disappeared are those situated close to the median tooth 

 (" Zwischenplatten " of Troschel). The median teeth themselves 

 have a long median denticle, and on either side a short acute den- 

 ticle, so that they resemble those of Onychoteuthis rather than of 



^ Compare Pelseneer, " Valeiir morphol. cles bras, &c. . . . cles C^ph.," Arch, 

 de Biol. viii. fig. a. 



^ Brock, op. cit. p. 22(i, pi. xi. fig. 7. 



^ ' Mollusca regionis arcticffi Norvegiaj,' pi. xyii. fig. 2 (1878). 



* Troschel, " Mundtbeile d. Ceph.," Arch. f. Naturg. xix. i. p. 11, pi. i. fig. 6. 



° Brock, op. cit. pi. xii. fig. 10 C. 



