406 Dr. J. E. Gray on the Arrangement of the Families 



that I have arrived at. The last and best arrangement of the 

 Melanosperms I have seen is Dr. Harvey's, published in his 

 1 Nereis Boreali-Americana/ vol. iii. Feb. 1858. But the know- 

 ledge of the fructification of Algse in general, and of this group 

 in particular, is still so imperfect, and the accounts given of it 

 by different authors are so conflicting, that it is by no means 

 easy to reconcile them and bring them into a general system. 

 The fructification of so small a proportion of the species has 

 been examined and well described, that it is very doubtful 

 whether many of the species which are referred to the different 

 genera really belong to them ; and in many genera the fruit has 

 been so imperfectly described, that it is doubtful to what family 

 they should be referred. 



Under these circumstances, I feel that any attempt at arranging 

 the families into larger groups must be attended with consider- 

 able uncertainty, and that we can only hope to advance towards 

 a good arrangement by very slow degrees, adding very gradually 

 to our knowledge as we proceed. 



In forming groups, we ought to observe the resemblances of 

 the species in their habits as well as in their properties and 

 structure. It is nearly an impossibility to define with absolute 

 strictness the confines of any group, of whatever value it may 

 be, whether a genus, a family, or an order ; and we must recol- 

 lect that the distinctness of a group does not depend on the 

 facility with which it can be characterized in a phrase or longer 

 description. To take an example from zoology : no one doubts 

 the distinctness of the Rabbits from the Hares ; yet every zoo- 

 logist and anatomist has failed to give a scientific character by 

 which they can be separated — and most countries have their 

 own species of hares or rabbits. I have known experienced 

 sportsmen puzzled to say whether the variety of the Rabbit 

 called the Leporine is a Hare or a Rabbit, and call some ani- 

 mals of the same litter hares, and others rabbits ; yet they are 

 most distinctly marked in their habits, as Mr. Bartlett justly 

 observes. The Hares, which live in a " form " above ground, 

 have the young born with the eyes open, covered with hair, 

 and ready to feed themselves a few hours after birth, as is also 

 the case with the Guinea Pig; while the Rabbits live in 

 burrows, have the young born blind and naked, and dependent 

 on their mother's milk for support for some time after birth. 

 Now, if this is the case with animals so well known, what must 

 be the imperfection of our knowledge regarding Algse, which we 

 can only observe at distant periods, and which are often so 

 minute as to escape our sight without the aid of glasses, and 

 many of which are greatly transformed in external appearance 

 during their life and growth ! 



