There are three main types of chinchilla that you are likely to come across some more often than others.  The ones to be found in the UK are the Langiera and the Brevicaudata.

They are:

Langiera

This species of chinchilla was mainly found in the mid levels of their natural habitat.  They have also been decribed as the best breeders in comparison to their chinchilla cousins mentioned below.  The original Langiera species showed a wider range of colours ranging from a bluish grey to a brown colouring.  This is the species that is still found in its natural habitat today although their numbers have become greatly diminished since man first discoverd them.  Purebred Langiera have been described as having long thin heads and shoulders and long ears and tails.  The other name i have heard them descrribed as is pointed heads, although i cannot recall who or where i read it but when i first encountered chinchillas i heard them described as round heads or pointed heads.  The Langiera has a gestation period of around 111 days see available online gestation calculators for a calculated date via the National Chinchilla Society Website.

Brevicaudata 

The next species we are more common with is the Brevicaudata which hails from the higest regions of the mountains.  They have described as the larger of the three species and have larger bodies and a broad head (the round head is what i have heard them called when i first started with chinchillas) .  They also have bluish ears and shorter tails than their Langiera cousins.  The purebreeds of this species was described as having a brownish tinge to their fur and a wavy appearance and texture to their longer fur.  This chinchilla was particularly well furred and had a good full neck which is two of the aspects that breeders, particularly ones who show their chinchillas,  try to maintain and perfect in their herds.

Costina

This is the last type of the three that inhabits the domestic world of chinchillas.  These types were found closest to sea level in their native region of the Andes.  Their characteristics were that they had longer ears and tails and are decribed as being more highly strung than the otehr two species.  This may be because in their native land with being at such a low level they had to be more alert to man or intruders and were the more susceptible of the three.  They are also desribed as having a pointed head and narrow body similar to the Langiera type.  Costina have been described as having contributed the rich blue fur colour to the domestic chinchilla.  Their fur is short and not as dense as the Brevicaudata but had a favourable good strength.