134 



ON' THE ANATOMY OF GONATUS FABRICII. [Mar. 5, 



this. The presence of a phragmocone, the absence of the nuchal 

 muscle, the form of the median tooth of the radula, and the presence 

 of nidamental glands are all points of considerable importance, 

 whilst the size of the anterior salivary glands is merely a matter of 

 degree, and the form of the anal appendages in the adult Gonatus is 

 unknown. The fusion of the median retractors in one is, so to 

 speak, balanced by their separation from the lateral retractors in the 

 other. The other remaining point, namely the opening of the 

 oviducts into special cavities in Onychoteuthis, does not seem suffi- 

 cient in itself to contravene the resemblances on the other side. 



Summary. 

 In addition to the general sketch of the anatomy of an interesting 

 form, the preceding pages record the existence of several tracts of 

 cartilage hitherto unobserved in the Cephalopoda, and give details 

 regarding the structure of the pen-sac and the development of the 

 pen, as well as new facts regarding the structure of the funnel-organ. 

 The genus Gonutus is regarded as being somewhat more nearly related 

 to Onychoteuthis than to Enoploteuthis, but as much further removed 

 from both than they are from each other. The creation of the sub- 

 family Gonatidce is held to be justified. 



In conclusion, I have lo fulfil the pleasant duty of thanking Mr. 

 Robert Gray for some of my materials, Professor Huxley for his 

 kindness in allowing me the use of his workroom, and Professor 

 G. B. Howes for the friendly interest he has taken in my work and 

 for numerous acts of kindness during its performance. 



EXPLANATION OF THE PLATES. 



These letters have the same signification ihroxighout. 



Their stem cut short. 



Foramen for the nerve to the 

 osphradium. 



Vein probably from the ovary. 



Pen. 



Pallial vein. 



" Pancreas." 



Posterior aorta. 

 "P-gt. Pei'icarclial gland. 

 l).n. Pallial nerve. 



Pedo-visceral ganglia. 



Posterior vena cava. 



Rectum. 



Eenal sacculi on the veins. 



Ridge for pallio-siphonal ar- 

 ticulation. 



Stomach. 



Rudimentary septum of the 

 phragmocone. 



Stellate ganglia. 



Supra-nuchal cartilage. 



Sujjra-gladial cartilages. 



Ventricle. 



Vena cava. 

 v.f.^ v.f". Venous foramina in the 

 cephalic cartilage. 



a. Anus. 

 a.ao. Anterior aorta. 



hr. Gills. 

 hr.a. Branchial artery. 

 br.h. Branchial heart. 

 hr.h' ., br.h". Branchial hearts. 

 b.g. Buccal ganglia. 

 br.g. Branchial ganglia. 

 br.v. Branchial vein. 

 c. Csecum. 

 ce. Cerebral ganglia. 

 CO.', co". Imier and outer limbs of the 

 coUaris muscle. 

 cp. Plug of cartilage in the hinder 



extremity of the pen-sac. 

 d.g. Digestive gland. 

 e', e". Epithelium of the pen-sac. 

 em. Epithelium of the mantle. 

 g. Articular groove on the 



siphon. 

 i.s. Ink-sac. 

 m.m. Retractores infundibuli. 

 mi. Nuchal cartilage. 

 od. Oviduct. 

 w. Oesophagus. 

 op. Optic ganglia. 



op\ 

 bsp. 



o.v. 



V- 



pall.v. 



pan. 



p.ao. 



p.v. 



p.v.c. 



r. 



re. 

 ri. 



sep. 



s.g. 



s.nw. 

 sw.g. 



V. 



v.c. 



