goldschmidt's monograph of amphioxides. 583 



Ampliioxides is remarkable for the possession of many 

 cliaracters which are proper to the larva of the European 

 species of Amphioxus, e. g. the absence of a closed atrial 

 chamber, a sinistral slit-like mouth, an unpaired series of 

 gill-clefts which lie in the mid-ventral line, an anterior dextral 

 endostyle, a club-shaped gland, and a sinistral prgeoral pit. 

 On account of these and some other characters the genus is 

 made the type of a new family, Amphioxididae Goldschmidt, 

 in contrast with the first family, Branchiostomidfe Bona- 

 parte, 1846. 



The characters mentioned above are regarded by Dr. 

 Goldschmidt as being essentially primitive, emphatically not 

 as indications of a persistent larval organisation. In other 

 words, in his opinion Amphioxides is the most primitive 

 Acraniate, and stands more or less in the direct line of 

 Vertebrate descent. 



One of the finest additions to our knowledge of the anatomy 

 of Amphioxus which has been made in recent years is 

 Professor J. W. van Wijhe's discovery of the sinistral inner- 

 vation of the mouth. Anyone who has handled Amphioxus 

 will probably subscribe to this statement. The conclusion 

 drawn by van Wijhe from this discovery and accepted by 

 Goldschmidt, namely, that the mouth of Amphioxus is from 

 the beginning to the end an organ of the left side, may seem 

 to be clearly indicated, and is held by Dr. Goldschmidt to be 

 a fact of primary phylogenetic significance in Amphioxides 

 where the sinistral position of the mouth is said to be 

 dependent upon the structure of the pharynx. It may be 

 mentioned here that my own theory is still what it was 

 fifteen years ago so far as its essential point is concerned, 

 that the mouth, or situs oris, of the lancelet has migrated 

 from a dorsal position such as it holds in the Ascidian larva. 



The pharynx of Amphioxides is characterised by the 

 presence in its floor of a median series of gill-perforations to 

 the number of thirty-four, opening directly to the exterior 

 on the ventral side of the body between the metapleural 

 folds. Above the gill-arches the wall of the pharynx projects 



