MONSTROSITIES 287 



When I visit the Fish Gallery of the Natural History IVTuseum 

 I feel a sort of conviction that many of the strange forms around 

 me must have commenced as monstrosities. 



The saw of the Saw-Fish {Prisiis) seems on the face of it to 

 have been a monstrosity ; the Spoonbill Sturgeon {Polypodon 

 spatula) ; the curious nose-process of Callorhynchus antarcticus , the 

 tailless Orthagoriscus oblongus, the enormous dorsal fin of one of 

 the Sword-fishes, Histophorus gladius, and so forth — all convince 

 me that these strange forms very probably commenced by a sudden 

 monstrosity. It is amongst fishes that we meet with such startling 

 abnormalities in large numbers. Scientists try to explain the 

 stump tail of a Puppy by calling it an ' arrest of development.' 

 That would mean that, ' it is what it is ' ! Any boy in the street 

 can tell us that such a Puppy ' has not a long tail, like other Dogs ! ' 

 But what is the cause of the arrest ? 



Mr. Stebbing in his Crustacea mentions that the male of 

 Gelasimus arenatus (De Haan) has one cheliped (claw), right or 

 left, monstrously enlarged. The very fact that it is sometimes the 

 right, and sometimes the left, which is so enlarged, would tend 

 to show that it is not by slow degrees that it attains that size, but 

 by some sudden derangement in the right or left nerve-centre that 

 controls the growth of the cheliped, and the Crab has to make the 

 best use of it. 



Monstrosities being congenital might easily be inheritable more 

 or less, provided the reproductive organs were efficient. So this 

 monstrosity in a certain Crab may become the fixed feature of a 

 whole race, which originally may have commenced by a sudden 

 evolution in one generation, and not by slow and gradual accumula- 

 tions of some slight variation. The study of fishes and Crustacea 

 would seem to afford quite a revelation, as to the probable origin 

 of many species. 



