34 



Spadella cephaloptcra Busch. 



W. Busch. Beobachtungen über Anatomie und Entwicklung einiger wirbellosen Seethiere. 



Berlin, 185 1, 4to. 

 Claparedi Grassi. 

 B. Grassi. Op. cit., p. 17. 



Specimens received from the Marine Biological Association at Plymouth, and from the 

 Scilly Islands sent by my friend Mr. Rupert V.\llentin, seem to leave no doubt of the 

 identity of the species of Busch and of Grassi. As the latter author himself points out (p. 18, 

 note) it is generally impossible to see all the teeth except in preparations made to that end, 

 which removes the chief discrepancy between the two descriptions; the other point which he 

 emphasises, the enlargement of the epidermal expansion behind the head, varies with the 

 amount and character of the death-contraction, and its effect on the width of the collarette 

 (compare p. 4 above). 



Characters. Head of medium size, marked off from the body by a distinct neck, 

 which however is obscured by the collarette. Two clavate papillae on the prepuce (lost in my 

 specimens). Collarette very broad just behind the head; its outline indented at the patches of 

 sense cells; behind the neck it narröws, but extends to the tail-septum, where its outline 

 becomes continuous with that of the lateral fins. Body firm, opaque, flattened dorso-ventrally, 

 thickest at about the septal region, more tapered forwards than backwards. Tail about 50 per 

 cent. of the total length. 



Lateral fins long, extending from the septum to the vesiculae seminales, of medium 

 width. Tail fin long, spatulate. 



Jaws slender, sometimes slightly saginate, their tips curved. The two rows of teeth are 

 very close together; the teeth irregularly set, blunt; the innermost tooth of the anterior row 

 is very long. 



Corona ciliata on the neck only; extending outwards over the collarette; with its long 

 axis transver.se to that of the body, either a regular oval (Grassi, Hertwig), or slightly waved 

 posteriorly (Busch) or markedly 'invaginated' posteriorly (specimens from Plymouth and Scilly); 

 very broad. Vestibular ridgc not seen. 



Formula : 5 : 50 : 8—9 : 3—5 : 3—4. 



In a carmine fjreparation, the corona exhibited two parallel bands of cells ; the outermost 

 with fine deeply .staining nuclei, of the same appearance as those of the patches of sense cells; 

 the innermost were larger and yellowish, and of a more glandular look. The specimen drawn 

 in figure 95 contained large closely appressed ova, evidently nearh' ripc; and at the mouths 

 of the oviducts were concave patches of glandular-looking cells. The characteristic adhesive 

 cells have been fully described and figured by Hkrtwu;. 



