70 Mr. P. Koorevaar on the 



visible in specimens preserved in spirit than in the fresh 

 larvae. 



The dimensions of these spinal larvae vary considerably ; 

 in a collection that I formed between October and Febrnary 

 there is one specimen measuring 5 millim. in length by 

 ^ millim. in breadth ; the remainder are from 6 to 14 millim. 

 long and from 1 to 2^ millim. broad. 



In the warm fat, before it has become solid, the larvae lie 

 extended ; if they are set free they assume a curved shape 

 and contract, becoming in consequence considerably shorter 

 and thicker; in this contracted condition the annulations are 

 also distinctly visible. As regards other details these grubs 

 have the characteristics of (Estrid larvse. 



In the year 1884 M. Hinrichsen, a veterinary surgeon, in 

 diss-ecting a tuberculous bullock, found the first specimen of 

 these larvas in the spinal canal ; in 1888 he published in the 

 ' Archiv fUr wissenschaftliche und praktische Thierheilkunde,' 

 Bd. xiv., an account of the examination of thirty-nine cattle. 



]n the case of fourteen of these (for the most part the 

 younger animals) he met with from one to twenty larvae in a 

 portion of the vertebral column. So long ago as 18B3 

 Prof. Brauer described and figured these larvse in his ' Mono- 

 graphic der CEstriden,' but the fact that they occur in numbers 

 in the spinal canal was nevertheless new. 



Further statements as to the finding of these larvae in the 

 neural canal in cattle are also given by Hinrichsen, Home, 

 and Euser in the 'Zeitschrift fiir Fleisch und Milchhygiene ' 

 for 1895. 



Hinrichsen considered these (EstrusAarvse to be the first 

 stage of .FJypoderma hovis, which was till then unknown ; 

 and Prof. Brauer agreed with this opinion. 



Owing to the frequent occurrence of this larva in the spinal 

 canal Home was led to consider the latter as the normal 

 hidden resting-place of Hypoderma hovis. 



In the middle of January I met with the first specimens of 

 Hypoder7na-\i\\\?e, beneath the skin ; on a closer examination 

 ten more (Estrus-\?^\\^ were found in the epidural fat of the 

 vertebral canal. 



'Ihe occurrence of Hf/podermaAarysd beneath the skin, in 

 what are known as warbles, and at the same time of (Estrus- 

 larvaj in the spinal canal in the same animal, was repeatedly 

 observed in the months of January, February, and March in 

 the slaughtered cattle at tiie abattoir. 



It is remarkable that in size and form the largest spinal 

 larvae do not difier from the youngest Bypoderma-Xskwad in 

 the subcutis ; the subcutaneous lar\ se are somewhat less 



